• ..;  • 


I  • ., 


n 


;vos  (•  epical      o^i 


THE 


MICEOSCOPE 


AND 


MICROSCOPICAL   TECHNOLOGY 


A  TEXT-BOOK 
FOE  PHYSICIANS  AND  STUDENTS. 

BY 

DR.    HEINRICH    FREY, 

\\  ' 

PROFESSOR  OF  MEDICINE  IN  ZURICH,   SWITZERLAND. 

TRANSLATED  FROM  THE  GERMAN  AND  EDITED  BY 

GEOEGE  E.  CUTTER,  M.D., 

CLINICAL  ASSISTANT  TO  THE  NEW  YORK  EYE  AND  EAB  INFIRMARY. 


ILLUSTRATED  BY  343  ENGRAVINGS  ON  "WOOD,   AND  CONTAINING  THE  PRICE-LISTS  OF  THE  PRIN- 
CIPAL MICROSCOPE-MAKERS  OF  EUROPE  AND  AMERICA. 


FROM  THE  FOURTH1  AND  LAST  GERMAN  EDITION. 


NEW  YOEK: 

WILLIAM    WOOD    &    CO., 

27  GREAT  JONES  STREET. 

1872. 


ENTERED  according  to  Act  of  Congress,  in  the  year  1872,  by 

WILLIAM  WOOD  &  CO., 
In  the  Office  of  the  Librarian  of  Congress,  at  Washington,  D.  C. 


POOLE  &  MACLAUCHLAN,  PRINTERS, 

205-213  East  Tieelfth  St., 

NEW  YORK. 


CONTENTS 


PAGE 

TRANSLATOR'S  PREFACE / v 

INTRODUCTION vii 

SECTION  FIRST. 
THEORY  OF  THE  MICROSCOPE 1 

SECTION   SECOND. 
APPARATUS  FOR  MEASURING  AND  DRAWING 34 

SECTION   THIRD. 

THE  BINOCULAR,  THE  STEREOSCOPIC,  AND  THE  POLARIZING  MICRO- 
SCOPE      49 

SECTION  FOURTH. 
TESTING  THE  MICROSCOPE 55 

SECTION   FIFTH. 

USE  OF  THE  MICROSCOPE — MICROSCOPIC  EXAMINATION 87 

SECTION   SIXTH. 
THE  PREPARATION  OF  MICROSCOPIC  OBJECTS 107 

SECTION   SEVENTH. 
FLUID  MEDIA  AND  CHEMICAL  REAGENTS — TITRITION 120 

SECTION  EIGHTH. 

METHODS  OF  STAINING — IMPREGNATION  WITH  METALS — THE  DRYING 
AND  FREEZING  PROCESSES 150 

SECTION  NINTH. 

METHOD  OF  INJECTING.  .  .169 


IV  CONTENTS. 

SECTION   TENTH.  PAGE 

THE  MOUNTING  AND  ARRANGEMENT  OF  MICROSCOPIC  OBJECTS 204 

SECTION   ELEVENTH. 
BLOOD,  LYMPH,  CHYLE,  Mucus,  AND  Pus 229 

SECTION   TWELFTH. 
EPITHELIUM,  NAILS,  HAIR 251 

SECTION  THIRTEENTH. 
CONNECTIVE  TISSUE  AND  CARTILAGE 269 

SECTION   FOURTEENTH. 
BONES  AND  TEETH 292 

SECTION   FIFTEENTH. 
MUSCLES  AND  NERVES 312 

SECTION   SIXTEENTH. 
VESSELS  AND  GLANDS 376 

SECTION   SEVENTEENTH. 
DIGESTIVE  ORGANS 417 

SECTION  EIGHTEENTH. 
PANCREAS,  LIVER,  AND  SPLEEN 458 

SECTION  NINETEENTH. 
RESPIRATORY  ORGANS 487 

SECTION   TWENTIETH. 
URINARY  ORGANS 505 

SECTION   TWENTY-FIRST. 
SEXUAL  ORGANS , 539 

SECTION   TWENTY-SECOND. 
ORGANS  OF  SENSE 560 

INDEX..  < 615 

PRICE-LISTS  OF  MICROSCOPE-MAKERS .   629 


TRANSLATOR'S  PREFACE. 


AISTY  attempt  on  my  part,  by  way  of  introduction  or 
commendation  of  Professor  Frey's  work,  must,  I  feel,  be 
altogether  misplaced  and  unnecessary.  Although  the 
treatise  has  been  but  a  few  years  before  the  public, 
four  large  editions  have  already  been  issued,  and  a  copy 
is  always  found  on  the  table  of  those  microscopists 
who  are  able  to  read  it  in  the  original. 

I  have  been  induced  to  undertake  the  arduous  labor 
of  preparing  a  translation  of  the  work  by  the  hope  that 
it  might  stimulate  and  facilitate  the  study  of  this  im- 
portant branch  of  science  in  this  country. 

An  apology  may  be  thought  necessary  for  the  style 
of  the  translation, — in  having  followed  the  German  so 
literally.  The  nature  of  the  subject,  however,  involving 
as  it  does  such  very  minute  descriptions,  and  the  fre- 
quent repetition  of  the  same  terms,  added  to  the  im- 
possibility of  doing  justice  in  any  other  way  to  the 
author's  condensed  style,  have  necessitated  a  rigid 
adherence  to  the  original  text. 

The  few  additions  which  have  been  made  are  enclosed 
within  brackets. 

GEORGE  R.  CUTTER,  M.D., 

No.  228  East  12th  St.,  New  York. 
OCTOBER,  1872. 


INTRODUCTION. 


"  To  endeavor  to  discover  new  methods  of  investigation  appears  to  me  to  be 
one  of  the  most  important  duties  of  every  observer.  To  communicate  these 
to  his  pupils  must  be  the  desire  of  every  teacher  of  any  branch  of  natural 
science." — (L.  Beale.  How  to  Work  with  the  Microscope,  p.  3.) 

WITHIN  the  last  ten  years  the  Microscope,  that  instrument  which 
has  conquered  a  new  world  of  minuteness  for  natural  science,  has 
become  widely  known.  Already  a  considerable  number  of  these  in- 
struments are  yearly  issued  from  the  large  and  celebrated  establish- 
ments of  Europe ;  and  not  less  noticeable  is  the  number  of  those  which 
are  constructed  and  sold  by  less  renowned  opticians.  The  opinion  is 
now  admitted  that  the  microscope  is  quite  as  indispensable  for  the 
scientific,  as  the  stethoscope  and  pleximeter  for  the  practical  require- 
ments of  the  physician. 

Through"  Schwann's  classical  work  we  have  learned  that  the  human 
body  is  formed,  in  all  its  parts,  from  cells  and  their  derivatives,  and 
that  the  cell  is  the  ultimate  organized  unity  of  animal  life.  As  in  the 
province  of  anatomy  we  cannot  understand  the  structure  of  any  por- 
tion of  the  body  without  this  little  microscopical  foundation-stone, 
even  so  little  do  we  succeed  in  comprehending  the  physiological  action, 
if  we  disregard  the  isolated  action  of  these  ultimate  organized  unities. 
The  united  action  of  an  organ  is  only  the  result  of  all  the  single  ac- 
tions of  cells,  of  the  "  elementary  organisms,"  as  they  were  afterwards 
called.  Thus  Histology  has  become  an  indispensable  member  in  the 
series  of  anatomico-physiological  sciences. 

Health  and  disease  appear,  in  the  ingenuous  view  of  man,  to  be 
separated  by  a  wide  abyss ;  an  opinion  which,  in  the  domain  of  science, 
is  drawn  like  a  red  thread  through  so  many  nosological  systems  of 
former  days.  The  recognition  of  the  contrary  is  properly  greeted  as  a 


Vlll  INTRODUCTION. 

great  advance  in  physiological  opinion.  The  processes  which  take 
place  in  the  diseased  body  are  actually,  for  us,  but  modifications  of 
those  which  occur  in  the  normal ;  the  same  physiological  laws  obtain 
in  the  one  case  as  in  the  other ;  and  those  also  which,  in  a  material 
regard,  occur  in  the  diseased  body,  the  metamorphosis,  separation,  and 
new  formation  of  its  elements,  obey  the  same  laws  of  cell-life  which 
we  recognize  in  the  normal  organism.  The  eminent  significance  of 
pathological  histology  requires  no  wider  discussion,  nor  is  it  necessary 
further  to  recommend  the  instrument  by  means  of  which  histology  is 
chiefly  created. 

Microscopy  is,  however,  as  some  of  our  readers  will  have  already 
experienced  in  their  first  attempts,  delicate  work.  How  many  a 
student,  how  many  a  physician,  impelled  by  the  great  value  of  such 
studies,  has  procured  a  microscope  only  to  perceive,  to  his  great  dis- 
satisfaction, how  little  he  is  qualified  to  use  it.  Here,  as  in  all  depart- 
ments of  human  efficacy,  a  period  of  apprenticeship  is  necessary, — 
an  arduous  season  of  sowing  before  attempting  to  reap  the  plenteous 
harvest. 

The  microscope  is  a  delicate  implement ;  like  other  complicated  in- 
struments, its  use  must  be  learned.  The  faculty  of  seeing  with  it  must 
likewise  be  acquired,  which  also  requires  some  perseverance,  if  we 
would  attain  to  the  accurate  vision  which  is  here  indispensable. 

The  art  to  observe  and  investigate  requires  the  employment  and 
knowledge  of  many  small,  and  therefore,  at  first,  apparently  unimpor- 
tant accessories.  The  time  is  past  when  it  was  thought  possible  to 
fathom  the  finer  textural  relations  of  a  piece  of  fresh  tissue  by  picking, 
and,  perhaps,  the  assistance  of  pressure  and  a  little  acetic  acid! 
Modern  chemistry,  to  which  medicine  is  extremely  indebted,  has  also 
furnished  the  microscopist  with  a  series  of  the  most  important  acces- 
sories. Thus,  now-a-days,  knives  and  needles,  the  syringe,  the  scales, 
and  many  other  artifices  are  employed  in  the  investigation  of  the  tissues 
of  the  body. 

We  shall  readily  comprehend,  from  what  has  been  said,  that  our 
so  industrious  epoch  in  a  microscopical  regard,  among  many  sound 


INTRODUCTION.  IX 

investigations,  also  annually  produces  over-hasty  performances  which 
show  how  little  their  authors  have  learned  to  overcome  the  most 
elementary  difficulties. 

This  remark,  however,  is  not  written  to  discourage ;  it  should,  on 
the  contrary,  only  indicate  that  the  most  complete  familiarity  with  the 
instrument  and  with  the  entire  technique  should  be  the  indispensable 
preliminary  of  every  microscopical  investigation. 

Though  that  school  which  offers  the  practical  instruction  of  a  teacher 
is  always  the  best,  it  is  not  permitted  to  every  one  to  walk  in  this  path 
to  learning.  Here  written  directions  find  their  place,  and,  provided 
they  are  judicious  and  practical,  may  afford  a  sufficient  compensation, 
and  make  a  microscopical  observer  out  of  the  beginner. 

The  literature  of  the  microscope  is  already  voluminous.  Admira- 
ble and  copious  works  exist  in  the  German,  Hollandish,  and  English 
languages,  such  as  those  of  Mohl,  Harting,  and  Carpenter.  But  in  the 
German  there  is  a  great  deficiency  of  concise  works  especially  adapted 
to  the  practical  wants  of  the  physician,  as  we  have  only  the  obsolete 
work  of  Vogel.  L.  Beale  has  produced  two  able  text-books  for  the 
English. 

May  our  little  work  serve  as  a  guide  for  students  and  physicians 
till  the  time,  at  least,  when  a  better  pen  shall  produce  a  better  substi- 
tute. 

That  we  premise  the  mechanism  of  the  instrument  and  the  use  of 
its  several  parts  is  obviously  necessary ;  for  a  knowledge  of  the  im- 
plements must  always  precede  the  labor  which  they  are  to  perform. 
That  we  limit  ourselves,  in  this  section,  to  that  which  is  most  impor- 
tant and  indispensable,  and  touch  but  lightly  the  difficult,  and  in  all 
its  parts  by  no  means  definitely  settled,  optical  theory,  requires  no 
further  justification.  Another  portion  of  our  work  treats  of  the  vari- 
ous methods  of  investigation  at  present  in  use.  A  third  part,  finally, 
completes  the  directions  for  investigating  the  various  tissues  and  parts 
of  the  body  in  a  normal  and  pathological  condition.  Possibly,  in  the 
department  of  pathology  we  may  have  been  too  concise  for  a  portion  of 
our  readers.  The  investigation  of  sputum,  pus,  urinary  sediment,  and 


X  INTRODUCTION. 

tumors  usually  occupies  a  much  larger  space  in  books  on  this  subject. 
But,  true  to  our  maxim,  that  the  most  accurate  knowledge  of  the 
normal  relations  should  precede  every  investigation  of  their  patholo- 
gical condition,  we  endeavor,  first  of  all,  to  make  the  former  clear  and 
then  join,  the  latter  supplementarily.  As  every  pathological  new 
formation  repeats,  more  or  less,  the  type  of  the  normal  structure,  so 
are  the  methods  of  investigating  diseased  tissues  and  portions  of  the 
body  almost  the  same. 

With  regard  to  the  literature  of  the  microscope,  we  would  particu- 
larly mention  the  following  works : — 

J.  Vogel,  Anleitung  zum  Gebrauche  des  Mikroskops,  Leipzig,  1841. 
— H.  v.  Mohl,  Mikrographie,  Tubingen,  1846. — C.  Robin,  Du  micro- 
skope  et  des  injections,  Paris,  1871. — P.  Harting,  Das  Mikroskop,  2. 
deutsche  Originalausgabe,  besorgt  von  Theile,  3  Bde.,  Braunschweig, 
1866. — W.  Carpenter,  The  Microscope,  4th  Edition,  London,  1868. — 
L.  Beale,  How  to  Work  with  the  Microscope,  4th  Edition,  London, 
1867,  and,  The  Microscope  in  its  application  to  practical  Medicine,  3d 
Edition,  London,  1866. — H.  Schacht,  Das  Mikroskop,  3.  Auflage, 
Berlin,  1862. — C.  NageliundS.  Schwendener,  Das  Mikroskop,  Leipzig, 
1867. — L.  Dippel,  Das  Mikroskop  und  seine  Anwendung,  Braunsch- 
weig, Bd.  1,  1867,  und  Bd.  2,  Abth.  1,  1869. 


Scrtian  .first 


THEORY  OF  THE  MICROSCOPE. 

THAT  wonderful  organ,  the  human  eye,  has  often  been  com- 
pared to  the  camera  obscura,  and  the  comparison  is,  indeed,  an 
excellent  one.  As  the  collective  lens  projects  an  inverted  di- 
minished image  at  the  background  of  the  latter  apparatus, 
which  is  received  on  the  ground-glass  plate,  so  the  collective 
refracting  media  of  the  eye  produce  the  same  inverted  dimin- 
ished image  at  its  profundity,  which  is  received  on  the  retina. 

Probably  all  of  our  readers  are  aware  that  the  dimensions 
which  an  object  appears  to  the  eye  to  possess,  depend  upon  the 
size  of  the  angle  of  vision ;  an  angle  which  one  receives  by 
combining,  through  straight  lines,  the  corresponding  terminal 
points  of  the  object,  and  of  the  image  received  in  the  eye. 

A  glance  at  fig.  1  will  render  this  intelligible.     The  curved 


Fig.  1.  Visual  angle  and  apparent  magnitude  of  the  object. 

line  at  b  a  represents  the  image,  projected  upon  the  fundus 
oculi,  of  the  arrow  A  B,  placed  before  the  organ  of  vision ;  a  is 
united  by  a  line  to  A,  5  by  a  second  one  to  B.  Thus  arises 
the  visual  angle  A  o  B  =  boa.  All  bodies  whose  terminal 


"2  SECTION"   FIRST. 

points  touch  the  lines  A  a  and  B  b,  appear  to  the  eye  to  be  of 
the  same  size.  A  needle  held  close  before  the  eye  may,  under 
these  circumstances,  have  the  same  apparent  dimensions  as  a 
long  pole  which  stands  in  the  distance.  When  the  arrow  is 
brought  nearer  to  the  eye,  to  A'  B'  for  instance,  it  projects  the 
image  b*  a*,  causing  the  angle  of  vision  A'  o  B' ;  the  arrow, 
however,  appears  to  be  larger.  If  the  angle  of  vision  falls  be- 
low a  certain  size,  the  object  ceases  to  be  visible.  A  thick 
wire,  for  example,  if  considerably  removed  from  our  eye,  is  no 
longer  perceived.  If  we  bring  the  wire  nearer  and  nearer, 
whereby  the  visual  angle  is  also  increased,  it  appears  at  first 
as  a  fine  thread,  then  with  increasing  diameter.  We  therefore 
instinctively  examine  small  objects  at  a  certain  proximity. 

But  a  continued  approach  also  finds  its  limit  at  last;  the 
wire,  which  was  still  distinctly  seen,  becomes  indistinct,  and 
filially,  having  been  brought  quite  close  to  the  eye,  becomes 
entirely  invisible. 

On  what  does  this  last  condition  depend  ? 

It  is  known  that  the  image  of  an  object  projected  by  a  col- 
lective lens  alters  its  position  according  as  the  object  is  removed 
from  or  brought  nearer  to  the  lens.  In  the  first  case  the  image 
approaches  the  lens,  in  the  latter,  it  recedes  farther  behind  it. 
Now,  as  the  human  eye  acts  in  the  same  manner  as  a  lens,  and 
accurate  vision  only  occurs  when  the  rays  of  light,  coming  from 
any  point  of  an  object,  are  so  refracted  as  to  be  again  united  at 
the  retina,  so,  in  reality,  a  distinct  image  can  only  be  possible 
at  a  certain  distance.  But  daily  observation  teaches  us  some- 
thing further;  we  see  remote  and  near  objects,  one  after  an- 
other, with  equal  accuracy.  The  eye  must,  therefore,  possess 
a  correcting  apparatus,  in  order  to  adjust  its  refracting  media 
for  proximate  and  remote  bodies;  it  accommodates,  as  the 
physiologists  say. 

This  process  of  accommodation  is,  however,  disregarding  in- 
dividual variations,  limited.  The  image  of  an  object,  brought 
more  and  more  near  to  the  eye,  falls  at  last  behind  the  retina. 
In  our  fig.  2,  the  arrow  placed  at  A  would  give  a  distinct  image, 
the  rays  of  light  diverging  from  a  point  p  being  united  at  a 
point  T  on  the  retina. 


THEOEY    OF    THE    MICKOSCOPE.  3 

Should  the  arrow,  however,  be  brought  so  near  as  B  to  the 
organ  of  vision,  this  union  can  no  longer  take  place  at  the  retina. 
The  rays  of  light  proceeding  from  p*  come  together  farther 
behind  this  membrane,  at  /•*. 


Fig.  2.    Position  of  an  object,  and  union  of  the  rays  which  proceed  from  it  in  the  eye. 

Yery  small  objects,  therefore,  when  brought  too  near  to  the 
human  eye  become  invisible ;  here,  as  we  shall  soon  see,  other 
accessories  are  necessary. 

The  distance  from  the  eye  at  which  objects  of  medium  size 
can  be  most  sharply  discerned,  is  called  the  mean  distance  of 
vision.  This  is  usually  considered  to  be  from  8  to  10  inches,  or 
25  centimetres,  for  the  normal  eye.  The  closest  proximity  at 
which  an  object  is  still  visible  is  called  the  near  point.  Kear- 
sighted  eyes  permit  of  a  few  inches  nearer  approach,  far-sighted 
ones  find  their  limit  sooner ;  the  first  refract  more,  the  latter 
less  strongly. 

Such  a  small  body  may,  however,  readily  be  made  visible  by 
placing  a  convex  lens  between  it  and  the  eye.  The  reason  is 
easily  understood.  The  point  placed  at  O,  fig.  3,  produces  its 


Fig.  3.    Action  of  a  convex  lens  when  an  object  is  brought  near  the  eye. 

image  at  r,  and  is  therefore  no  longer  perceptible  to  the  eye. 
If  we  now  place  the  lens  L,  whose  focus  is  at  F,  between,  the 
rays  of  light  receive  the  direction  indicated  by  the  dotted  lines, 


4  SECTION    FIRST. 

are  less  divergent  on  reaching  the  eye,  and  are,  consequently, 
united  on  the  retina  at  K.  Thus  a  distinct  image  is  formed. 

It  will  also  be  observed,  that  by  the  use  of  such  a  lens  the 
image  thus  received  is  enlarged. 

Now  whence  does  this  arise  ? 

Let  us  suppose  that  the  object  is  placed  at  AB,  fig.  4,  and 
that  a  convex  lens  is  brought  between  it  and  the  eye.  The  cone 
of  rays  which  proceeds  from  any  point  of  the  arrow,  for  exam- 
ple from  A,  projects  its  rays  A  J,  A  C,  A  c  on  to  the  lens,  and 
these^  with  the  exception  of  the  rays  A  C,  are  refracted  by  the 


Fig.  4.    An  object  magnified  by  a  convex  lens. 

lens  in  the  direction  l>  I  and  c  i  /  receiving  a  slight  divergence, 
as  if  they  proceeded  from  the  more  distant  point  A*,  they  arrive 
at  the  eye  and  are  united  on  the  retina.  The  same  is  repeated 
for  the  cone  of  rays  B,  etc. ;  thus  an  inverted  image  of  the 
arrow  is  formed  in  the  eye.  The  object  appears  to  the  organ  of 
vision  to  be  placed,  not  at  A  B,  but  at  A*  B*,  and  therefore 
enlarged.  As  a  proof  that  the  image  caused  by  a  convex  lens 
is  always  apparently  more  remote  than  the  object  itself,  look  at 
a  piece  of  paper  through  the  lens,  and  attempt  to  touch  the  edge 
of  it  with  the  point  of  a  needle.  The  needle  will  invariably  be 
directed  some  distance  beneath  the  paper. 

Such  convex  lenses  are  usually  called  loups,  so  long  as  their 
magnifying  power  does  not  exceed  15  or  20  diameters,  and  so 
long  as  during  their  use  they  can  be  guided  by  the  human  hand. 
When  the  magnifying  power  of  such  lenses  is  greater,  so  that  a 
stand  is  necessary  to  support  them  during  their  use,  the  combi- 


THEORY    OF   THE   MICROSCOPE.  5 

nation  is  called  a  simple  microscope.  The  impossibility  of 
making  a  sharp  line  of  demarcation  between  the  two  kinds  of 
instruments  is  self-evident,  as  weak  convex  lenses  are  also  fast- 
ened to  a  stand,  and  numerous  so-called  loup-supporters  are  also 
employed  (fig.  5). 


Fig.  5.    Nachet's  simple  loup-stand. 


There  are  many  varieties  of  loups,  but  we  must  refer  to  more 
detailed  works  for  their  description.  Their  value  and  applica- 
tion in  natural  philosophy  is  also  too  well  known  to  render  it 
necessary  for  us  to  say  more  on  the  subject.  A  good  loup,  mag- 
nifying 10  or  15  times,  is  indispensable. 


Fig.  6.    PlossTs  simple  microscope. 


The  simple  microscope  of  Plossl,  of  Vienna,  is  seen  in  fig. 
A  metal  bar  (a)  supports,  at  half  its  height,  a  horizontal 


6  SECTION   FIKST. 

plate  which  is  bored  through  its  centre,  the  stage  (5)  of  the  mi- 
croscope. This  can  be  elevated  or  depressed  by  means  of  the 
rack  (c).  The  movable  mirror  (f)  placed  beneath,  serves  to  re- 
flect the  light  on  to  the  object  to  be  examined,  which  is  placed 
on  the  stage.  If,  instead  of  transmitted  light,  it  be  desired  to 
examine  the  object  by  reflected  light,  after  the  manner  of  our 
usual  vision,  the  mirror  is  thrown  out  of  action,  or  an  opaque 
plate  is  placed  on  the  stage.  The  horizontal  arm  (d),  on  the 
tipper  extremity  of  the  stand,  carries  the  magnifying  glass,  the 
lens  (e).  It  can  be  removed  from  the  opening  in  the  arm  and 
replaced  by  another. 

The  simple  microscope  of  Nachet,  of  Paris  (fig.  7),  likewise 
has  a  convenient  form.  The  movement  is  made  by  a  rack, 
which  elevates  or  lowers  the  lens,  in  contradistinction  to  the 


Fig.  7.    Nachetfs  simple  microscope. 

stand  of  Plossl,  in  which  the  stage  moves  up  and  down.  Two 
additional  plates  on  the  stage,  bent  downwards,  serve  as  supports 
for  the  hands  during  the  manipulation.  Both  instruments  have 
clamps  on  the  stage,  for  the  purpose  of  fixing  the  object. 

The  simple  microscope  is  now-a-days  indispensable  to  the 
natural  philosopher,  as  an  instrument  for  dissecting.  It  is, 
however,  no  longer,  or  but  little,  employed  for  scientific  investi- 
gations. 

When  a  tube  is  placed  over  the  magnif ying-glass  of  the  simple 
microscope,  and  the  object  is  placed  somewhat  beyond  the  focus 
of  the  lens,  an  enlarged,  inverted  image  of  the  same  is  projected 


THEORY    OF   THE    MICROSCOPE.  7 

within  the  tube.  In  fig.  8  we  can  readily  perceive  this  relation. 
If  we  connect  the  lens  L  with  a  funnel,  whose  diameter  extends 
from  e*  to  d*,  we  may  receive  the  image  on  a  ground  glass  plate. 
When  this  aerial  image  is  again  enlarged  by  means  of  a  con- 
vex lens,  we  have  the  compound  dioptrical  microscope.  The 
difference  between  these  two  instruments  consists  in  this,  that 


Fig.  8.    The  compound  microscope  in  simplified  form. 

in  the  simple  microscope  the  object  itself,  in  the  compound,  on 
the  contrary,  the  enlarged  image  of  the  object  is  seen.  Our 
fig.  8  may  represent  the  compound  microscope  in  its  simplest 
form.  The  united  cone  of  rays  c*  a*  b*  diverge  from  the  ele- 
vation e*  d*  to  the  upper  lens,  from  whence,  after  their  refrac- 


8  SECTION   FIRST. 

tion,  they  arrive,  under  a  slight  divergence,  at  the  human  eye. 
At  the  same  time,  however,  we  find  that  the  cone  of  rays  which 
proceed  from  the  terminal  points  d  and  e  of  the  arrow,  are 
united  at  d*  and  0*,  they  do  not  arrive  at  the  upper  lens.  We 
perceive,  therefore,  in  our  example,  only  the  length  ~b-c  of 
the  arrow.  A  smaller  arrow,  circumscribed  in  this  dimension 
(see  lower  part  of  fig.  8),  would,  on  the  contrary,  be  distinctly 
seen.  The  dotted  lines,  which  pass  to  c**  and  &**,  the  pro- 
longation of  the  rays  refracted  by  the  upper  lens,  give,  at  the 
same  time,  the  apparent  size  under  which  the  arrow  l>  c  is  seen. 

An  explanation  of  the  image  c*  a*  5*  of  the  arrow  is  neces- 
sary, in  one  other  regard ;  it  appears  curved,  wiiile  the  arrow 
itself  is  straight.  If  WQ  hold  it  as  established  that  the  point  of 
union  of  a  cone  of  rays  falls  farther  behind  the  lens  from  a  near 
object  than  it  does  from  one  lying  more  remote;  and  if  we  re- 
member that  b  and  d,  c  and  e  are  situated  farther  from  the  optical 
middle  point  than  «,  then  we  can  readily  understand  why  the 
surface  of  the  image  is  curved. 

The  knowledge  of  magnifying-glasses  and  the  art  of  grinding 
them  already  existed  in  antiquity  and  the  early  middle  ages. 
The  invention  of  the  compound  microscope  occurred,  on  the 
contrary,  at  a  considerably  later  epoch.  There  is  110  longer  any 
doubt  that  an  humble  Hollandish  spectacle"  grinder,  Zacharias 
Janssen,  of  Middelburg,  probably  about  the  year  1590,  produced 
the  first  instrument  of  this  kind.  Other  authorities  mention, 
without  sufficient  foundation,  the  Netherlander,  Cornelius  Dreb- 
bel,  Galilei  and  another  Italian,  Fontana,  as  the  discoverers. 
Harting,  with  his  usual  carefulness,  investigated  this  question  of 
the  invention  several  years  ago. 

The  oldest  compound  microscopes  were,  however,  very  incom- 
plete instruments,  and  were  encumbered  with  great  optical  defi- 
ciencies. These  imperfections  rendered  themselves  sufficiently 
perceptible  with  weaker  powers,  and  attained,  with  somewhat 
stronger  glasses,  such  a  rapid  increase  as  to  render  the  whole 
combination  nearly  useless. 

In  order  to  understand  this,  we  must  recall  to  our  minds  a 
few  well-known  optical  principles. 

The  term  angle  of  aperture  of  a  lens  denotes  the  angle  which 


THEORY   OF   THE   MICROSCOPE.  9 

is  formed  by  the  focus  and  the  two  terminal  points  of  the  dia- 
meter of  the  lens.  Thus,  gfh  is  the  angle  of  aperture  of  our 
fig.  9.  Only  so  long  as  this  angle  remains  small,  do  the  peri- 
pheral and  central  rays  actually  reunite  in  a  point,  as  we  have 
thus  far,  for  the  sake  of  greater  simplicity,  assumed.  "When  the 


D 

Fig.  9.    Spherical  Aberration. 

angle  of  aperture  is  greater,  only  those  rays  of  light  (BB)  which 
are  nearly  parallel  to  the  axis  (A)  of  the  lens,  and  which  pass 
through  its  central  portions,  are  united  at  the  focus  F,  while 
those  rays  (CC)  which  pass  nearer  the  periphery  of  the  lens  are 
more  strongly  refracted  and  find  their  focus  already  in  f. 
This  property  of  refraction  is  called  the  spherical  aberration. 

If  we  cause  the  rays  which  proceed  from  a  small  luminous 
body  to  pass  through  such  a  lens,  we  receive  at  F  the  image  pro- 
jected by  the  central  rays.  It  is  not  sharp,  however,  but  is  sur- 
rounded by  a  halo  or  circle  of  diffusion,  caused  by  the  peripheral 
rays,  which  have  become  divergent  again.  If  we  apply  a  dark 
disk  with  a  circular  opening,  a  so-called  diaphragm  or  stop 
DD,  the  peripheral  rays  are  intercepted,  and  we  receive  a  dis- 
tinct though  faintly  illuminated  image  at  F;  also  aty,  when  we 
obstruct  the  central  rays,  and  thus  permit  only  the  peripheral 
rays  to  pass  through  the  lens.  Such  annular  diaphragms  are 
extensively  employed  in  practical  optics,  for  the  purpose  of 
improving  the  images. 

"We  here  mention  another,  for  the  theory  of  the  microscope, 
important  effect  of  this  spherical  aberration.  When  very  small 
cones  of  rays  arrive  at  a  convex  lens  of  considerable  diameter, 
as  is  the  case  with  the  ocular  O  in  fig.  8,  those  which  pass 
through  the  periphery  of  the  lens  necessarily  receive  a  stronger 
refraction  than  the  more  central  ones.  The  peripheral  points 
of  the  image  must,  accordingly,  appear  nearer  each  other  than 


10 


SECTION   FIRST. 


the  internal  portions.  A  wire  network,  fig.  10,  presents  an  aerial 
image,  such  as  is  represented  by  fig.  11.  If  we  observe  the 
quadrangular  network  through  such  a  loup  we  receive  a  diame- 
trically opposite  phantom,  after  the  manner  of  our  fig.  12. 
In  both  cases  arises,  therefore,  a  distortion  of  the  image. 


Fig.  10.    Quadratic  network.          Fig.  11.    Image  distortion.          Fig.  12.    Image  distortion. 

A  second  not  less  palpable  inconvenience  in  the  use  of  such 
lenses  arises  in  consequence  of  their  chromatic  aberration. 


Fig.  13.    Chromatic  Aberration. 

A  ray  of  white  light  (fig.  13,  B  or  C),  in  passing  through  a 
convex  lens  would  not  be  refracted  as  a  whole,  but  would  be 
decomposed  into  rays  of  various  colors,  which  suffer  deviation 
in  varying  degrees  in  the  direction  of  the  plane  of  refraction, 
and  thus  form  a  spectrum,  at  one  extremity  of  which  the 
strongest  refracted,  the  violet  (v\  and  at  the  other,  the  least 
deviated,  the  red  ray  (r)  appears. 

From  what  has  just  been  said  it  follows,  that  with  ordinary 
convex  glass  lenses  we  perceive  the  object  indistinctly  defined 
and  surrounded  with  colored  borders.  Both  faults  increase 
rapidly  with  the  increase  of  curvature  of  the  lenses.  The  older 
microscopes,  therefore,  produced  images  which  were  faintly 
illuminated,  insufficiently  defined,  and  surrounded  with  colored 
borders.  The  image  projected  by  an  imperfect  object  lens  was 
still  further  magnified  by  the  likewise  imperfect  ocular  lens. 


THEORY    OF   THE    MICKOSCOPE.  11 

Achromatic  lenses  have  now  taken  the  place  of  the  old  use- 
less glasses.  By  this  name  is  indicated  such  with  which  the 
foci  of  the  various  colored  rays  of  light  are  united,  in  other 
words,  those  which  show  the  object  free  from  colored  borders. 

The  powers  of  refraction  and  of  dispersion  are  not  united  in 
equal  proportions  in  any  single  refractive  medium,  as  has  been 
known  for  a  long  time.  One  medium  gives,  in  the  same  power 
of  refraction,  a  greater  deviation  to  the  colored  rays  than  an- 
other. There  are  two  different  kinds  of  glass  which  act  in  this 
manner  with  regard  to  each  other — crown-glass  and  flint-glass. 
The  latter  is  partly  composed  of  lead,  and  has  a  considerably 
greater  power  of  dispersing  the  colored  rays  than  the  former. 

If  we  combine  a  bi-convex  crown-glass  lens  with  a  plano- 
concave flint-glass  lens  (both  are  generally  cemented  together 
with  Canada  balsam)  we  obtain  a  combination  in  which  the 
refraction  of  the  convex  crown-glass  lens  is  lessened,  but  not 
destroyed,  by  the  dispersive  action  of  the  flint-glass  lens.  At 


Tig.  14    Achromatic  lens. 

the  same  time,  however,  the  color  dispersion  (v  r,  fig.  14)  of  the 
crown-glass  lens  is  neutralized  by  the  contrary  action  of  the 
flint-glass  lens,  so  that  the  violet  and  red  rays  are  accurately 
united  in  F,  at  the  central  focus  of  the  lens.  The  image  here 
produced  will  either  be  colorless  or  have  its  natural  color. 

Such  a  combination  presents,  at  the  same  time,  an  expedient 
by  which  the  spherical  aberration  may  also  be  substantially 
improved. 

A  double  lens,  with  which  the  spherical  as  well  as  the 
chromatic  aberration  is  annulled,  is  usually  called  aplanatic. 
But  in  reality  it  is  impossible  to  completely  obviate  either  the 
spherical  aberration  (for  reasons,  to  discuss  which  here  would 
lead  us  too  far)  or  the  chromatic,  for  even  when  the  violet 


12  SECTION   FIRST. 

and  red  marginal  rajs  are  made  to  unite,  the  ratio  of  the  dis- 
persion of  the  various  colored  rays  of  the  spectrum  is  never 
entirely  equal. 

Should,  therefore,  even  with  a  double  lens,  the  violet  and  red 
rays  of  light  be  united,  the  edges  of  the  image  would  still  ex- 
hibit traces  of  the  uhunited  central  rays  of  the  spectrum.  The 
edges  appear  greenish  yellow.  It  is  customary,  therefore,  in 
the  construction  of  double  lenses  for  the  microscope,  to  give  a 
slight  preponderance  to  the  flint-glass  lens,  so  as  to  obtain  a 
bluish  tinge,  which  is  more  agreeable  to  the  eye ;  the  double 
lens  is  then  said  to  be  over-corrected.  A  double  lens  is  under- 
corrected  when  a  reddish  border  is  perceptible. 

As,  in  regard  to  color  dispersion,  one  speaks  of  over-  and 
under-correction,  the  same  mode  of  expression  is  also  used  in 
speaking  of  the  correction  of  spherical  aberration. 

While  the  discovery  of  achromatism  had  already,  in  the  mid- 
dle of  the  previous  century,  led  to  the  production  of  improved 
telescopes,  the  smallness  of  the  object  lens  disco nraged  the 
microscope-makers  from  making  the  same  experiment  on  the 
latter. 

According  to  Harting's  statement,  the  Hollander,  Hermann 
Yan  Deyl,  produced  the  first  achromatic  microscope,  in  a  very 
satisfactory  manner,  in  the  year  1807.  Four  years  later,  Fraun- 
hofer,  the  renowned  optician  of  Munich,  supplied  achromatic 
instruments.  In  the  year  1824  the  two  Chevaliers  of  Paris,  un- 
der the  direction  of  Selligue,  combined  for  the  first  time  several 
achromatic  objective  lenses  into  one  system.  The  Italian  Amici, 
of  Modena,  then  acquired  an  immortal  renown  in  the  sphere  of 
microscopical  improvements.  Other  opticians  followed  him 
with  worthy  emulation,  among  which,  for  the  end  of  the  first 
half  of  the  present  century,  we  will  particularize  only  Plo'ssl, 
of  Yiernia  ;  Schiek,  of  Berlin  ;  and  Oberhauser,  of  Paris.  The 
instrument  soon  became  as  useful  and  complete  as  that  of  the 
eighteenth  century  was  unserviceable  and  incomplete.  The 
commencement  of  the  great  and  brilliant  era  of  modern  micro- 
scopy is  cotemporary  with  these  improvements  of  the  instru- 
ment. But  the  recent  past  has  also  presented  many  permanent 
and  important  improvements,  as  we  shall  hereafter  see. 


THEORY    OF    THE   MICROSCOPE. 


13 


Let  us  return,  however,  to  the  mechanism  of  our  instrument. 

If  we  glance  at  fig.  8,  we  shall  perceive  that  the  image  of  the 
arrow  produced  by  the  achromatic  lens  is  now  free  from  colored 
borders  and  the  spherical  aberration  essentially  corrected,  but 
the  incurvation  and  distortion  of  the  same,  as  well  as  the  dimin- 
utiveness  of  the  field  of  vision,  that  is,  the  plane  surveyed  by 
the  eye-piece,  remains  as  before. 


7//lll\\\ 


Fig.  15.    The  compound  microscope  with  a  field-glass. 

Among  the  accessories  which  are  employed  for  further  cor- 
rection is  a  very  old  one,  namely,  the  introduction  of  another 
convex  lens  into  the  tube  of  the  microscope.  This,  fig.  15,  C, 


14  SECTION   FIRST. 

is  placed  between  the  objective  L  and  the  ocular  O,  so,  how- 
ever, as  to  occupy  a  position  beneath  the  point  of  union  c*  a*  b* 
of  the  cones  of  rays  refracted  by  the  objective  lens  from  the 
object. 

The  advantage  obtained  by  the  introduction  of  such  a  convex 
lens  or  field-glass  is  manifested  in  various  ways.  Firstly,  the 
rays  proceeding  from  the  points  5  and  c  of  the  arrow  are  re- 
fracted by  the  convex  lens  towards  its  axis,  as  may  be  seen  in 
the  figure.  Without  the  field-glass  the  image  would  be  pro- 
jected at  c*  a*  #*,  too  much  extended  to  be  surveyed  from  the 
ocular  lens.  An  image  is  now  projected  at  0**  &**  #**  which, 
though  not  so  large,  still  comprises  the  entire  arrow.  Secondly, 
the  clearness  of  the  image  is  increased  by  the  field-glass,  as  all 
the  rays,  which,  without  this  lens,  would  have  produced  the 
image  c*  a*  #*,  are  now  united  in  the  smaller  space  of  the 
image  c**  a**  £**.  Thirdly,  such  a  field-glass,  in  connection 
with  the  ocular,  may  serve  to  improve  the  correction  of  the 
spherical  and  chromatic  aberration.  Fourthly — and  in  this  lies 
a  great  advantage — the  field-glass  obviates  the  distortion  of  the 
image  and  the  unequal  enlargement  of  the  various  portions  of 
the  field  of  vision  connected  with  it.  As  we  have  already 
learned,  the  rays  passing  through  the  marginal  portions  of  the 
lens  are  more  strongly  refracted  than  those  passing  through  its 
central  portions,  in  consequence  of  the  spherical  aberration,  and 
the  axial  and  peripheral  points  of  the  image  approach  each  other 
proportionately  (fig.  11).  Now,  as  the  ocular  lens,  for  observ- 
ing the  aerial  image  c**  a**  £**,  exerts  exactly  the  contrary 
effect  (fig.  12)  by  its  considerable  diameter,  the  entire  correction 
may  be  obtained  by  the  proper  use  of  an  ocular  and  a  field- 
glass  (fig.  10). 

These  various,  and,  for  the  most  part,  highly  important  ad- 
vantages secured  by  the  addition  of  a  field-glass  render  it  appre- 
ciable that  the  latter  is  no  longer  omitted  in  any  of  the  com- 
pound microscopes  of  the  present  time,  and  that  it  has  become 
an  integral  element  of  all  its  combinations. 

We  have  remarked  above  that,  since  the  year  1824,  the  indi- 
vidual achromatic  double  lenses  are  combined  with  each  other 
into,  so-called,  systems.  Yarious  advantages  are  thereby  ob- 


TIIEOKY    OF   THE    MICROSCOPE.  15 

tained.  It  is  very  difficult  to  construct  a  double  lens  of  crown 
and  flint  glass  with  a  short  focus,  while  several  weaker  ones 
combined  give  the  same  magnifying  power  as  the  simple  objec- 
tive, and  are  much  easier  to  make.  Then,  as  we  have  also  seen, 
by  the  combination  of  a  single  crown  and  flint  glass  lens, 
whereby,  also,  a  small  angle  of  aperture  must  always  be  given 
to  the  lens,  the  spherical  and  chromatic  aberration  are  essentially 
lessened,  but  not  entirely  obviated.  By  a  suitable  combination 
of  several  double  lenses,  where  the  aberrations  of 
one  lens  are  made  to  correct  the  opposite  ones  of  an- 
other, a  considerable  further  correction  is  obtained, 
and  a  much  larger  angle  of  aperture  may  be  used ; 
in  this  manner  the  greatly  improved  lenses  of  our 
microscopes  of  the  present  day  are  produced.  In 
these  only  two,  or,  at  most,  three  double  lenses  are 
combined  with  each  other  (fig.  16). 

The  earlier  opticians  generally  designated  the 
several  double  lenses  by  a  series  of  numbers,  1,  2, 
3-6,  the  weakest  bearing  the  lowest  number,  and  Fi  16  An 
screwed  them  together  into  a  system  (for  example,  ?^S?™a*^  °{J 
1,  2,  3,  and  4,  5,  6).  In  this  way,  with  a  moderate  £gieeofnaper- 
number  of  single  lenses,  a  series  of  systems  may  be 
constructed,  it  is  true;  but  two  things  which  are  of  greater 
importance,  the  accurate  centering  (that  is,  the  falling  together 
of  the  axes  of  the  lenses  in  a  single  straight  line)  and  the  proper 
distancing  of  the  single  lenses  from  each  other,  cannot  be  so 
accurately  accomplished  as  -where  these  are  permanently  com- 
bined with  each  other  in  systems.  The  preference  has,  there- 
fore, very  properly  been  given  to  the  latter  arrangement,  and, 
though  the  former  is  the  least  expensive,  it  should  be  entirely 
discarded.  The  permanent  systems  are  variously  designated  by 
the  opticians ;  either  by  numerals  increasing  with  the  strength 
of  the  combination,  or  by  a  series  of  letters.  The  manner  of 
expression  of  the  English  opticians  is  peculiar.  They  speak  of 
i~>  i~>  yV"?  A"  °^  an  mcn  combinations  of  lenses,  making  the  in- 
crease of  the  strength  of  their  systems  the  same  as  that  of  a 
simple  lens  of  £,  -|-,  y^,  ^  inch  focus. 

The  combination  of  the  three  achromatic  lenses  with  each 


16  SECTION    FIRST. 

other  is  such  that  the  strongest  and  smallest  lens  is  turned 
downwards  and  the  weakest  upwards  (fig.  16).  A  somewhat 
greater  focal  distance  is  thus  obtained,  and  such  angles  of  aper- 
ture may  be  given  to  the  lenses,  that  all  the  rays  of  a  cone  of 
light  c  a  b  received  by  the  lower  lens  may  also  pass  through 
the  entire  combination  of  lenses.  Only  in  this  way  has  it  been 
possible  to  give  the  above-mentioned  high  angle  of  aperture  to 
the  objectives,  which  must  naturally  increase  the  brightness  of 
the  image,  and  besides,  as  we  shall  see  hereafter,  considerably 
increase  the  intrinsic  power  of  the  combination  also. 

The  ordinary  eye-piece  of  our  microscopes  (fig.  17,  O),  also 
called  the  Huyghenian  or  negative  eye-piece,  consists  of  a  longer 
or  shorter  tube  carrying  at  its  upper  end  the  plano-convex  lens 
A,  whose  plane  surface  is  turned  towards  the  eye  of  the  ob- 
server, while  the  plano-convex  lens  C,  with  its  curved  surface 
also  turned  downwards,  is  screwed  into  the  lower  end  of  the 
tube.  The  aerial  image  P*  falls,  as  we  have  seen,  between  the 
field  and  ocular  glass.  Every  microscope  is  supplied  with  sev- 
eral such  eye-pieces  of  various  strengths,  designated  by  num- 
bers. The  eye-pieces  become  shorter  in  proportion  to  the 
increase  of  their  magnifying  power.  Another  form  is  called 
the  Ramsden,  or  positive  eye-piece.  It  also  consists  of  two 
plano-convex  lenses ;  but  their  curved  surfaces  are  turned 
towards  each  other,  and  they  lie  nearer  together.  Here  the 
image  does  not  fall  between  the  field  and  ocular  glasses,  but  lies 
at  a  short  distance  beneath  the  former.  The  latter  eye-piece  is, 
however,  but  little  used. 

Kellner's  orthoscopic  eye-piece  is  a  modification  of  that  of 
Huyghens,  or  the  negative ;  its  field-glass  is  bi-convex.  It  pre- 
sents a  very  large  field  free  from  image  distortion  without,  how- 
ever (and  in  this  I  must  agree  with  Harting),  appreciably  in- 
creasing the  optical  power. 

Hartnack  has  recently  constructed  a  new,  strong  eye-piece, 
the  oculaire  holostere.  It  consists  of  a  single  conical-shaped 
piece  of  glass,  after  the  manner  of  the  Coddington  lens,  and 
magnifies  about  ten  times.  It  has  thus  far,  however,  presented 
me  no  considerable  advantages. 

In  order  to  render  the  Huyghenian  eye-piece  as  free  as  pos- 


THEORY    OF   THE    MICEOSCOPE. 
A 


17 


B     /»* 


Pig.  17.    The  compound  microscope. 


sible  from  spherical  and  chromatic  aberration,  it  has  been  pro- 
posed to  make  it  aplanatic  and  to  combine  it  with  an  aplanatic 
objective  system.     Such  aplanatic  eye-pieces  are  to  be  found 
2 


IS  SECTIOX   FIRST. 

with  many  instruments.  Their  magnifying  power  is  weak  and 
the  field  of  vision  small. 

The  usual  arrangement  is  different.  It  consists  of  the  use  of 
eye-pieces  which  are  by  no  means  entirely  aplanatic,  and  the 
aberration  present  in  the  eye-piece  is  made  to  correct  the  oppo- 
site aberration  of  the  lens  system.  Objectives  of  somewhat 
over-corrected  chromatic,  and  also  spherical  aberration  are  com- 
bined with  under-corrected  eye-pieces.  An  objective  which  was 
rendered  as  aplanatic  as  possible  would,  on  the  contrary,  if 
combined  with  one  of  the  ordinary  eye-pieces,  produce  an  im- 
perfect image.  While  therefore  aplanatic  lenses  are  necessary 
for  the  loup  and  the  simple  microscope,  the  art  in  the  produc- 
tion of  a  compound  dioptrical  microscope  rests  directly  in  the 
removal  of  the  aberrations  of  the  objective  by  means  of  the  con- 
trary aberrations  of  the  eye-piece.  It  is  only  thus  that  an  image 
free  from  defects  may  be  obtained,  in  a  manner  similar  to 
that  already  mentioned  of  correcting  one  double  lens  of  an 
aplanatic  system  by  means  of  the  other. 

In  eye-pieces  the  distance  of  the  field-glass  from  the  ocu- 
lar lens  is  of  importance.  If  the  former  glass  is  made  to  ap- 
proach the  latter,  the  aerial  image  is  greater ;  if  the  latter  glass 
be  made  to  approach  the  former,  it  is  smaller.  The  opticians, 
as  a  rule,  fix  both  the  glasses  of  an  eye-piece  in  an  unchangeable 
position ;  they  select  the  ones  offering  the  most  advantageous 
action.  The  length  of  the  tube  of  the  microscope,  which  in 
increasing  also  increases  the  magnifying  power,  is  likewise  of 
importance  to  the  advantageous  combined  action  of  the  ocular 
and  objective  systems.  Less  increase  in  the  length  of  the  micro- 
scope tube  is  permissible  with  a  higher  degree  of  over-correc- 
tion of  the  lenses  than  with  a  weaker  one. 

Still  another  element  is  associated  with  the  optical  relations 
enumerated,  for  a  knowledge  of  which  we  have  to  thank  Amici. 
At  the  present  time  it  receives  due  attention,  whereas  for  a  long 
time  it  was  entirely  ignored.  We  refer  to  the  thickness  of  the 
scale  of  glass  with  which  it  is  customary  to  cover  the  object  for 
microscopical  examination.  The  thickness  of  the  glass  cover 
exerts  considerable  influence  on  the  sharpness  of  the  image, 
especially  when  strong  lenses  are  used.  An  object  which,  un- 


THEORY    OF   THE    MICEOSCOPE. 


19 


covered,  or  with  a  very  thin  glass  cover,  presents  a  sharp  image, 
becomes  somewhat  dim  and  foggy,  and  the  appreciability  of  its 
details  diminishes,  if  a  thicker  cover  be  used.  Inversely,  many 
lenses  only  manifest  their  highest  capabilities  when  a  covering 
glass  is  used. 

Now,  on  what  does  this  influence  of  the  cover  depend,  and 
what  are  the  means  for  its  correction  ? 

Let  P,  fig.  18,  be  a  thick  glass  plate,  and  a  a  point  of  light 
from  which  proceeds  a  cone  of  rays.  The  rays  on  entering  the 


Fig.  18.    Effect  of  the  covering-glass. 

glass  will  be  refracted  in  various  degrees.  The  external,  most 
obliquely  incident  rays  af  and  a  g  will  be  the  most  strongly 
refracted  and  will  assume  the  directions  ff*  and  g  <?*,  the 
more  internal  rays  a  d  and  a  e  will  be  less  influenced,  and  the 
more  central  rays  a  b  and  a  e  will  be  still  less  deflected  from 
their  course.  On  emerging  from  the  glass  the  most  external 
rays  are  refracted  in  the  direction  f* /**  and  g*  g**,  the  more 
internal  ones  in  the  direction  d*  d**  and  e*  €**,  and  those  most 
internal  in  the  direction  &*  J**  and  c*  c**.  The  luminous  spot 
will  appear  to  the  eye  as  though  it  were  seen  nearer  in  the 
glass,  and  instead  of  one  luminous  point  a  series  of  points  ]ying 
over  each  other  will  seem  to  be  present ;  as  h  for  the  rays  b  and 
c,  i  for  d  and  <?,  Jc  for/* and  g.  If,  instead  of  a  point,  we  have 
an  object,  it  will  make  an  impression  as  if  it  consisted  of  a  series 
of  images  lying  over  each  other.  We  receive,  therefore,  the 
same  effect  as  from  spherical  aberration,  and  in  a  degree  which 
increases  with  the  thickness  of  the  glass  covers.  It  will  there- 

O 


20  SECTION    FIRST. 

fore  be  appreciable  how  imperfect  such  a  course  of  the  rays  of 
light  must  render  the  image  of  an  object  with  a  lens  which  is 
arranged  for  uncovered  objects  ;  for  the  same  reason,  an  objec- 
tive constructed  by  the  optician  for  a  covered  test  object  will 
only  develop  its  perfect  action  when  a  suitable  cover  is  used. 
Weaker  combinations  manifest  this  influence  of  the  glass  covers 
only  in  a  minor  degree,  however ;  stronger  ones,  on  the  con- 
trary, in  a  very  appreciable  manner. 

This  influence  of  the  cover  may  be  counteracted  by  changing 
the  length  of  the  microscope  tube,  and  also  by  altering  the  dis- 
tance between  the  ocular  and  field  glasses.  It  is  advisable,  in  a 
practical  point  of  view,  to  use  a  system  with  its  appropriate 
covers  only,  and  to  have  special  thicknesses  of  glass  for  each 
system. 

Another  method  is  now  becoming  more  generally  adopted. 
By  changing  the  position  of  the  individual  lenses  of  a  combina- 
tion this  action  of  the  glass  cover  may  be  obviated,  and  thus  one 
and  the  same  system  may  be  employed  either  for  uncovered 
objects  or  for  such  as  have  covers  of  various  thicknesses.  For 
this  purpose  the  individual  double  lenses  of  a  system  are  ar- 
ranged so  that  their  relative  positions  may  be  changed  by  means 
of  a  fine  screw ;  thus  the  observer  is  enabled  to  make  the  neces- 
sary change  at  any  moment.  Such  combinations  are  called 
objectives  with  correcting  apparatus.  They  are  naturally  more 
expensive  than  ordinary  objectives  and  require  in  their  use  a 
certain  amount  of  practice  and  some  outlay  of  time,  but  the 
arrangement  is  almost  indispensable  for  very  high  powers. 
The  rule  is,  that  with  increasing  thickness  of  the  cover  the 
j  ,  individual  lenses  of  the  system  must  be 

PI          zRl  OL      Brought  nearer  to  each  other,  while  for 

very  *km  covers  they  must  be  moved 
farther  apart.     In  fig.  19, 1,  the  objec- 
tive  represented  with  a  correcting  ap- 
paratus  has  a  small  metallic  slider,  s, 
Fig.  19.  Achromatic  objective    which,  moving  up  or  down,  indicates 
the  various  positions  of  the  lenses.     It 
is  represented  at  2  a  ft  c  in  its  various  positions. 

Having  familiarized  ourselves  with  the  objective  and  the  eye- 


THEOKY    OF   THE    MICROSCOPE.  21 

piece,  we  are  now  in  condition  to  examine  more  closely  the  con- 
struction of  a  modern  compound  microscope. 

The  optical  portion  is  of  the  greatest  importance ;  the  arrange- 
ment of  the  stand  is,  on  the  contrary,  of  much  less  consequence. 
Good  lenses  with  suitable  eye-pieces,  placed  on  a  very  imperfect 
stand,  would  enable  an  observer  to  recognize  subtile  structural 
conditions  which  would  be  concealed  from  another,  whose  instru- 
ment combined  an  imperfect  optical  apparatus  with  a  very 
superior  mechanism.  Nevertheless,  disregarding  the  tediousness 
of  the  manipulation,  poor,  incomplete  stands  exert  an  imme- 
diately injurious  effect  on  the  optical  performances  of  a  micro- 
scope, by  not  permitting  of  the  necessary  modifications  of  the 
illumination. 

Every  modern  instrument  requires  several  objectives ;  namely, 
a  weak,  a  medium,  and  a  strong  one ;  the  combinations  of  each 
should,  preferably,  be  permanent.  Large  microscopes  have  a 
more  abundant  supply  of  objectives,  five  or  six,  and  even  more, 
and  among  them  the  most  powerful  ones,  in  the  production  of 
which  great  -proficiency  has  been  developed  of  late,  as  we  shall 
see  further  on.  These  very  high  powers  are  not  required  for 
ordinary  investigations,  and  can,  therefore,  be  more  readily  dis- 
pensed with  than  combinations  of  medium  strength. 

A  few  eye-pieces,  at  least  two,  are  necessary;  a  weak  one, 
magnifying  about  three  or  four  times,  and  a  stronger  one  of 
double  that  strength. 

It  might  readily  be  believed  that  a  considerable  number  of 
eye-pieces  with  increasing,  and,  finally,  with  very  high  mag- 
nifying power  would  be  of  advantage  to  our  instrument.  But 
this  is  erroneous.  Let  us  remember  that  an  enlarged  image 
would  be  projected  by  the  objective  L,  fig.  20,  into  the  tube  K, 
and  would  not  be  without  defects,  as  it  is  impossible  to  produce 
mathematically  correct  lenses.  The  image  would  be  magnified 
by  the  eye-piece,  and,  naturally,  its  imperfections  in  the  same 
proportion  also.  The  eye-piece  does  not,  therefore,  like  the 
objective,  permit  us  to  penetrate  more  deeply  into  the  structure 
of  the  object ;  it  only  enlarges  the  images  of  the  latter.  The 
use  of  somewhat  stronger  eye-pieces  has  the  advantage,  however, 
of  enabling  us  to  recognize  many  things  more  readily,  because 


22 


SECTION   FIRST. 


they  are  more  enlarged.     But  in  using  still  stronger  eye-pieces, 
we  soon  arrive  at  a  limit  where  the  image  is  impaired.     The 


C 


Fig.  20. 


most  beautiful  and  elegant  images  are  obtained  with  very  weak 


THEORY  -OF    THE    MICROSCOPE.  23 

eye-pieces.  Nevertheless  many  of  the  more  modern  lenses  bear 
considerably  stronger  eye-pieces  than  those  of  a  former  epoch, 
which  must  always  be  regarded  as  a  proof  of  superior  optical 
perfection. 

~No  further  observations  are  necessary,  therefore,  to  show  that 
it  is  impossible  to  compensate  for  the  poverty  in  lenses  of  a 
microscope  by  a  profuse  endowment  of  eye-pieces.  It  is  also 
evident  that  the  value  of  an  enlargement,  obtained  with  a 
stronger  objective  and  a  weaker  eye-piece,  stands  higher  than 
that  of  another,  where  a  strong  eye-piece  is  used  with  a  weaker 
objective.  Older  German  microscopes  frequently  have  only 
weak  objectives,  but  are,  oil  the  contrary,  furnished  with  several 
eye-pieces  of  too  great  strength.  This  is  to  be  regarded  as  a 
fault.  At  the  commencement  of  the  fifth  decade  of  this  century, 
for  example,  the  instruments  of  Schiek  compared  very  disadvan- 
tageously,  in  this  regard,  with  those  of  Oberhauser. 

The  tube  of  the  microscope,  as  well  as  that  of  the  eye-piece, 
has  its  inner  surface  blackened,  and  is  either  in  one  piece  (fig.  20, 
E)  and  therefore  incapable  of  extension,  or  it  is  composed  of  two 
pieces  which  glide  over  each  other,  after  the  manner  of  the  teles- 
cope. That  the  latter  is  to  be  regarded  as  the  better  arrangement 
is  proved  by  several  previously  mentioned  optical  principles. 

The  objective  (L)  is  to  be  fastened  on  to  the  lower  end  of  the 
tube  by  means  of  a  screw. 

The  stage  (T)  is  the  metal  plate  perforated  in  its  centre, 
already  described  in  speaking  of  the  simple  microscope,  for  the 
reception  of  the  object  (P.  E.)  to  be  examined.  The  stage 
should  not  be  too  small,  and  especially  not  too  narrow. 

Objective  and  object  must  be  capable  of  being  moved  from 
or  towards  each  other  as  circumstances  may  require.  All  com- 
pound microscopes  have  arrangements  for  this  purpose,  that  is, 
for  focussing  the  object.  Shoving  the  microscope  tube  with  the 
hand  through  a  metal  sheath  is  a  very  primitive  contrivance, 
and  is  only  practicable  with  weak  powers. 

Various  expedients  are  employed  for  more  accurate  alteration 
of  the  focus.  This  may  be  accomplished,  to  a  considerable 
extent,  by  means  of  a  single  mechanism,  when  the  latter  is  care- 
fully constructed.  In  fact,  the  older  instruments  frequently 


24 


SECTION   FIRST. 


have  no  other.  As  a  rule,  the  tube  of  the  microscope  is  made 
to  screw  up  and  down  on  its  support ;  less  frequently  employed, 
and  still  less  to  be  recommended,  is  a  movable  stage,  the  tube 
being  immovable. 

With  the  more  carefully  constructed  modern  stands  a  double 
mechanism  is  provided,  one  of  which  serves  for  the  coarse,  and 
the  other  for  the  fine  adjustment.  Such  a  distribution  of  the 
work  naturally  deserves  the  preference.  The  coarser  move- 
ments are  made  either  by  machinery ,  or,  what  answers  just  as  well 
and  is  more  practicable  by  reason  of  its  greater  simplicity,  the 
tube  of  the  microscope  may  be  moved  in  a  sheath  which  sur- 
rounds it,  by  the  hand.  The  finely  constructed  micrometer 
screw,  which  moves  the  microscope,  is  used  for  more  accurate 
focussing;  the  practised  observer  almost  never  removes  his 
hand  from  it  in  making  delicate  investigations  and  when  using 
the  higher  powers. 

Ordinary  incident  light  is  rarely  used  for  the  illumination  of 
the  object,  and  then  only  when  the  lowest  powers  are  employed. 
When  strong  illumination  is  required,  a  convex  lens  (a,  fig. 
21)  with  a  long  focus  is  employed.  It  should  be 
movable  in  various  directions,  and  placed  either 
on  a  stand  d  b  c,  or  on  a  ring  which  is  to  be  shoved 
over  the  tube  of  the  microscope. 

Objects  are  most  frequently  illuminated  by 
means  of  transmitted  light;  the  light  being  re- 
ceived on  a  mirror  (fig.  20,  S),  placed  beneath  the 
stage,  and  reflected  through  the  opening  to  the 
object  (P). 

The  mirror  must  be  fastened  to  the  stand  in 
such  a  manner  as  to  permit  of  the  greatest  free- 
dom of  movement.     The  arrangement  of  many  of 
the  smaller  instruments,  permitting  the  mirror  to 
move  around  its  horizontal  axis  only,  is  an  im- 
rig.  21.  ninmin-  portant  imperfection.      Small  microscopes  have 
,tmg  lens.       only  a  concave  mirror,  by  which  the  incident  rays 
(a  a)  are  reflected  in  a  convergent  direction  (b  b)  to  the  hole  in 
the  stage.     Larger  instruments  have  a  mirror  with  one  of  its 
surfaces  concave  and  the  other  plane.     The  latter  surface  gives 


THEORY    OF   THE    MICROSCOPE. 


25 


a  less  intensive  illumination  than  the  former  and  is,  therefore, 
more  frequently  used  with  the  weaker  powers. 

Careful  illumination  is  a  very  important  accessory  in  micro- 
scopical examinations,  and  is  not  to  be  obtained  with  the  above- 
mentioned  contrivances  alone.  Other  special  apparatuses  are 
consequently  necessary.  For  many  examinations,  especially  of 
delicate,  finely  bordered  objects,  the  light  reflected  through  the 
opening  of  the  stage  would  give  a  much  too  dazzling  illumina- 
tion. A  portion  of  the  rays  must  therefore  be  cut  off.  This  is 
accomplished  by  diminishing  the  opening  of  the  stage ;  for  this 
purpose  the  so-called  screens  or  diaphragms  are  used. 

Two  forms  are  employed;  the  rotary  and  the  cylindrical 
diaphragm.     The  rotary  diaphragm  (a,  fig.  22)  has  a  circular 
form    and    is    fastened    under    the    stage    by    means    of    a 
button.    A  series  of  cir- 
cular openings  diminish, 
with  the  exception  of  the 
largest,  the  aperture  of 
the  stage.    The  smallest 
holes  are  employed  with 
the  highest  powers. 

Cylindrical  dia- 
phragms are  cylindrical 
tubes  which  have  at  their 
upper  ends  a  circular 
disk  with  an  opening  of 
varying  size  (fig.  22,  b,  c).  They  are  inserted  into  the  opening  of 
the  stage,  either  immediately  or  by  means  of  a  socket.  To 
develop  their  complete  action,  some  contrivance  is  necessary,  by 
means  of  which  they  can  be  raised  or  lowered. 

Both  arrangements  accomplish  their  objects ;  but  the  cylin- 
drical diaphragm  deserves  the  preference,  as  it  permits  of  finer 
gradations  of  illumination.  On  many  of  the  older  instruments 
we  find  both  these  kinds  of  diaphragm  combined. 

For  many  purposes,  instead  of  the  ordinary  illumination, 
generally  called  central  light,  it  is  necessary  to  reflect  the  light 
from  beneath  in  a  more  or  less  oblique  direction  on  to  the  ob- 
ject, called  oblique  illumination.  For  this  purpose,  the  mirror 


Fig.  22.  Diaphragms,     a,  the  rotary  diaphragm ;  6,  c, 
cylindrical  diaphragms. 


26 


SECTION    FIRST. 


should  have  the  utmost  freedom  of  motion,  because  it  is  some- 
times necessary  to  give  it  a  very  lateral  position. 

A  further  modification  of  the  illumination  is  obtained  by  in- 
serting a  convex  lens  or  a  combination  of  lenses  into  the  aper- 
ture of  the  stage.  By  elevating  or  depressing  the  lens,  we 
may  cause  the  rays  of  light  coming  from  the  plane  mirror  to 
unite  in  a  focus  at  the  object,  or  to  arrive  at  it  in  a  divergent 
direction,  either  before  or  after  their  union.  A  concave  mirror, 
combined  with  such  lenses,  sometimes  affords  very  good 
illumination. 

Such  an  illuminating  apparatus,  consisting  of  achromatic 
lenses,  was  made  many  years  ago  by  Dujardin.  Considerable 
attention  was  afterwards  directed  to  these,  especially  by  the 
English  opticians,  who  called  them  condensers,  resulting  in  their 

essential  improvement.  A  conden- 
ser of  perfected  construction  is 
shown  in  fig.  23.  Below  it  is  a 
rotatory  diaphragm  which  is  capa- 
ble of  covering  a  greater  or  lesser 
portion  of  its  margin  and,  by  means 
of  several  openings,  darkening  the 
central  portion  of  the  lens,  which 

Fig.  23.      Achromatic  condenser  ot       CaUSCS    peculiar     effects,    resembling 
Smith  and  Beck.  €  .      '          . 

many  or  those  ot  oblique  light. 

I  have  recently  received  from  Hartnack  an  efficient  con- 
denser, quite  similar  to  the  illuminating  apparatus  former- 
ly constructed  by  Dujardin,  consisting  of  three  achromatic 
lenses.  Diaphragms  may  be  screwed  on  to  the  upper  lens. 
The  apparatus  is  to  be  inserted  into  the  stage  in  the  same 
manner  as  a  cylindrical  diaphragm. 

As  an  achromatic  condenser  is  expensive,  it  may  be  substi- 
2  /        tuted,  to  a  certain  extent,  by  an  or- 

dinary plano-convex  lens.  Fig.  24, 
1,  shows  such  a  one  inserted  into 
the  tube  of  an  ordinary  cylindri- 
cal diaphragm.  In  2,  it  is  cover- 

©d    by  a  black   ling,  SO    that    Ollly 

the  central  portion  remains  free 


Pig.  24.    Ordinary  condenser;  1  in  sec- 

^  *  blackrins;  3  with  a 


THEORY    OF   THE   MICROSCOPE.  27 

for  the  passage  of  the  rays  of  light ;  while  in  3,  a  small  black 
disk  obscures  the  central  part  of  the  lens,  leaving  only  the 
peripheral  portions  free.  The  latter  arrangement  is  to  be  re- 
commended to  those  whose  microscope  does  not  permit  the 
mirror  to  be  placed  obliquely.  The  whole  arrangement  is,  be- 
sides, the  least  expensive  of  any. 


in. 


Fig.  25.  Microscopes  of  Merz,  of  Munich.    III.  smallest,  II.  medium,  I.  large   instrument. 

As  we  shall  see  hereafter,  such  convex  lenses  are  necessary 
for  investigations  with  polarized  light,  as  well  as  when  the 
microscope  is  used  as  a  micro-photographic  apparatus. 

At  the  close  of  this  section  it  may  be  expedient  to  glance  at 
several  microscopes,  and  thus  obtain  a  few  examples  of  the 
various  methods  adopted  by  opticians  for  fulfilling  the  various 
indications. 

Fig.  25,  III.  shows  a  microscope  of  the  smallest  sort  made  by 
Merz,  of  Munich.  The  coarse  adjustment  is  made  by  shoving 


28 


SECTION   FIRST. 


the  tube  through  a  spring  sheath,  the  fine  movement  is  (inexpe- 
diently) accomplished  by  the  elevation  and  depression  of  the 
stage.  The  concave  mirror  permits  of  central  illumination 
only.  Fig.  26  represents  a  small  instrument  made  by  Nachet, 
of  Paris,  with  a  stand  which,  though  simplified,  is  much  more 
efficient  and  suffices  for  most  investigations.  Here,  also,  the 
microscope  tube  may  be  shoved  up  and  down  in  a  spring  sheath, 
and  thus  serves  for  the  coarse  adjustment.  The  fine  movement 


Fig.  26. 
Nachet's  small  microscope. 


Fig.  27. 
Chevalier's  small  microscope. 


Fig.  28. 
Zeiss'  small  microscope. 


is  obtained  by  means  of  a  screw-head  placed  at  the  upper  end 
of  the  stem.  The  stage  is  sufficiently  wide,  and  beneath  it  is  a 
rotary  disk  for  moderating  the  illumination.  Several  clamps 
on  the  stage,  intended  for  holding  the  glass  slides,  may  be 
removed  if  necessary.  The  mirror  is  fastened  to  the  round 
foot,  and  permits  of  great  freedom  of  movement.  It  may  be 
moved  away  from  the  axis,  and  thus  be  employed  for  oblique 


THEORY    OF    THE    MICROSCOPE. 


29 


illumination.  The  illuminating  lens  (placed  erect  in  the  figure) 
serves  for  illumination  with  incident  light.  The  smaller  micro- 
scopes of  Chevalier,  of  Paris,  fig.  27,  as  well  as  those  of  Zeiss,  of 
Jena,  fig.  28,  have  a  quite  similar  arrangement. 


Fig.  29.    Older  large  horse-shoe  microscope  of  Oberhanser  and  Hartnack. 

In  the  latter  instrument,  however,  the  suspension  of  the 
mirror  is  different,  and  the  rotary  disk  under  the  stage  is  convex 
on  its  upper  surface,  so  that  the  aperture  of  the  diaphragm  may 
come  as  close  as  possible  to  the  object.  Such  instruments, 
among  which  the  medium-sized  microscope  of  Merz,  fig.  25, 


30 


SECTION    FIRST. 


II.,  is  also  to  be  reckoned,  have  very  suitable  stands,  which  are 
frequently  imitated  by  other  microscope-makers  with  slight 
modifications.  Naturally  a  stand  may  be  still  further  simpli- 
fied, but  its  adaptability  to  various  kinds  of  examinations  is  im- 
paired, for  example,  when  the  oblique  illumination  is  omitted. 
The  large  horse-shoe  microscope  (fig.  29),  invented  l>y  Ober- 
hauser,  of  Paris,  has  one  of  the  most  efficient  stands.  It  has 
been  more  frequently  imitated  than  any  other  with  which  I  am 
acquainted,  and  combines  the  advantage  of  the  greatest  adapta- 
bility with  simplicity  of  construction. 


Fig.  30.    The  same  with  oblique  illumination. 


Fig.  81.    Hartnack's  small 
horse-shoe  microscope. 


In  the  old  stand,  the  coarse  adjustment  is  also  made  by  slid- 
ing the  tube  in  the  spring  sheath,  but  his  latest  instruments  are 
furnished  with  a  mechanism  for  this  purpose.  The  tube  itself 
is  capable  of  being  shortened.  The  fine  adjustment  is  made 
with  a  micrometer  screw  which  projects  beneath  the  stage  and 
runs  in  a  hollow  tube  containing  a  spiral  spring.  The  screw 
moves  a  second  tube  which  surrounds  the  former  and  is  joined 
to  the  sheath  of  the  microscope  tube.  The  diaphragms,  sur- 
rounded by  a  cylinder,  are  carried  by  a  so-called  sliding  plate, 


THEORY    OF    THE    MICROSCOPE.  81 

and  are  adjusted  by  raising  or  depressing  the  cylinder.  When 
one  diaphragm  is  to  be  replaced  by  another,  the  cylinder  is  to 
be  drawn  out,  armed  with  a  new  diaphragm,  and  replaced  from 
beneath  the  stage.  If  oblique  illumination  is  necessary,  the 
sliding  plate  with  its  entire  apparatus  is  to  be  removed. 


Fig.  32.    Large  microscope  of  Smith  and  Beck. 

With  the  latter  illumination  the  stage  may  be  rotated,  so  that 
the  obliquely  incident  rays  of  light  may  come  from  all  sides  on 
to  the  object.  The  mirror  works  on  a  square  piece  fitting  into 
the  embrasure  of  the  double  bar  which  supports  the  instrument, 
and  permits  of  the  most  varied  changes  of  position.  The  large, 
heavy  horse-shoe  foot  supports  the  whole.  An  illuminating 


32 


SECTION    FIEST. 


lens  on  a  separate  stand  (after  the  manner  of  fig.  21)  may  be 
placed  before  the  instrument. 

A  smaller  form  of  the  same  stand  (fig.  31)  dispenses  with  the 
rotary  stage,  and  does  not  permit  the  mirror  to  be  moved  up 
and  down  in  a  slit,  though  the  oblique  position  is  still  possible. 
This  stand  of  Hartnack's  is  very  good  and  at  the  same  time  ex- 
ceedingly cheap. 


Fig.  83.    Nachetfs  large  microscope,  most  recent  pattern. 

Both  stands  may  also  be  obtained  furnished  with  a  hinge  for 
inclining. 

Merz's  large  instruments  are  also  quite  similar  to  these,  as  is 
shown  in  fig.  25,  1. 


THEORY    OF    THE    MICROSCOPE.  33 

"We  also  notice  a  large  microscope,  fig.  32,  of  Smith  and  Beck, 
of  London,  as  an  example  of  an  instrument  which  is  much  more 
complicated  (too  much  so,  according  to  our  Continental  notions) 
in  its  structure.  Much  is  here  allotted  to  screws  which,  in 
Oberhauser's  stand,  is  done  by  the  human  hand.  The  instru- 
ment hangs  between  two  pillars  and  can,  therefore,  be  given  an 
oblique  or  horizontal  position.  The  mirror  permits  of  a  pretty 
free  movement.  The  stage  is  too  profusely  covered  with  ap- 
purtenances, but  permits  (and  in  this  lies  a  great  advantage  over 
Oberhauser's  instrument)  of  the  introduction  of  a.  perfected 
condenser. 

Kachet's  large  microscope  of  latest  construction  (fig.  33)  is 
likewise  remarkably  complicated,  but  its  mechanism  is  admi- 
rable. 


0cction 


APPARATUS  FOR  MEASURING  AND  DRAWING. 

IT  is  unnecessary  to  mention  how  important  the  measuring  of 
objects  seen  under  the  microscope  is  for  scientific  work.  In 
fact,  various  and,  in  part,  ingenious  methods  were  proposed  in 
the  infancy  of  microscopy  for  determining  the  size  of  objects. 
The  reader  will  find  more  on  this  point  in  the  excellent  work 
of  Harting. 

At  the  present  time,  we  have  measuring  apparatus  of  rela- 
tively greater  accuracy.  Two  forms  of  micrometers  are  to  be 
particularly  discriminated  ;  namely,  first,  the  screw  micrometer, 
and,  second,  the  glass  micrometer. 

The  screw  micrometer  is  a  somewhat  complicated  but,  when 
the  workmanship  is  good,  very  accurate,  and,  therefore,  also 
very  expensive  implement.  Its  arrangement  rests  upon  the  fol- 
lowing. If  a  cobweb  thread  is  drawn  across  the  eye-piece,  it  is 
self-evident  that  a  microscopical  object  may  be  so  guided 
through  the  field  of  vision,  by  means  of  a  stage  moved  by 
screws,  that  its  anterior  border  first  cuts  the  thread,  and  then 
gradually  passes  beyond  it,  till  at  last  only  the  posterior  margin 
of  the  object  exactly  touches  the  thread.  Now,  the  screw 
micrometer  is  such  a  movable  stage.  It  has  a  double  plate,  the 
upper  one  of  which  is  movable,  by  means  of  a  very  fine 
micrometer  screw,  over  the  lower  one,  which  is  fastened  to  the 
stage  of  the  microscope.  A  partial  view  of  this  arrangement 
is  afforded  by  fig.  25,  1.  The  extent  which  it  is  necessary  to 
turn  the  screw,  in  order  to  move  the  object,  in  the  manner 
indicated,  through  the  field,  may  be  read  from  the  index  of  the 
upper  plate  and  the  divisions  on  the  drum  of  the  screw.  The 
unities  of  these  screw  micrometers  vary.  Those  of  Plossl  give 
^  a  Vienna  inch,  those  of  Schiek,  T^  and  y^-^  of  a 


APPARATUS    FOE    MEASURING    AND    DRAWING.  35 

Parisian  line.  The  ocular  screw  micrometer  is  an  advantageous 
modification  of  the  screw  micrometer,  especially  the  improved 
form  described  several  years  ago  by  Mohl. 

Nowadays,  however,  the  expensive  screw  micrometers  are 
rarely  used ;  the  much  simpler  and  less  expensive  glass 
micrometers  are  used  in  their  stead. 

It  is  well  known  that  the  art  of  engraving  five  divisions  on 
a  glass  plate,  by  means  of  the  diamond  point,  has  made  great 
strides,  and  in  a  later  section  we  shall  see  the  marvellous  mani- 
festation of  this  skill  in  Robert's  test  plates. 

The  line  is  now  divided,  with  the  greatest  elegance,  into  100, 
500,  and  1,000  parts.  In  some  of  these  micrometers  the  lines 
are  all  of  equal. length;  those  are  better  in  which  the  greater 
divisions  are  indicated  by  longer  lines,  as  is  the  case  with  our 
ordinary  rules.  A  modification,  which  is  convenient  for  many 
purposes,  consists  in  the  crossing  at  right  angles  of  one  series  of 
lines  by  a  second  series,  generally  so  that  quadratic  spaces 
result. 

Now,  such  micrometers  are  capable  of  the  simplest  appli- 
cation as  object  bearers.  Let  us  assume  that  we  have  a  divi- 
sion where  the  value  of  each  space  is  -$%-$'",  it  is  self-evident 
that  a  microscopical  object  which  occupies  two  of  these  spaces 
is  -g-o-g-'",  and  another,  which  covers  five,  is  i^f"  in  size. 

However  efficient  these  methods  may  seem,  at  the  first  glance, 
to  be,  they  are  nevertheless  very  inconvenient,  and  it  is  therefore 
no  longer  customary  to  use  them.  First,  because  the  minuteness 
of  many  objects  requires  a  very  finely  divided  and  therefore 
very  expensive  micrometer.  Then,  in  cleaning  them  they  be- 
come injured  in  a  comparatively  short  time,  and  gradually  be- 
come seriously  impaired.  Further — and  this  is  of  much 
greater  moment  —  the  objects  to  be  measured  very  often  lie 
obliquely,  and  not  parallel  to  the  lines,  however  fortunately 
they  may  be  placed  on  the  micrometer.  Finally,  the  case  of- 
ten arises  where  it  is  necessary  to  estimate  the  value  of  a  frac- 
tion of  a  space,  whereby  the  eye  may  be  deceived. 

From  the  above  mentioned  it  will  be  conceivable  that  the  glass 
micrometer,  in  the  form  of  an  object  bearer,  has  been  discarded 
except  for  certain  special  purposes. 


36  SECTION   SECOND. 

These  micrometers  are  now  placed  in  the  eye-piece,  as  ocular 
micrometers,  in  the  form  of  circular  glass  plates.     They  lie  on 
its  diaphragm,  between  the  field  glass  and 
the  ocular  lens  (fig.  20,  B). 

Such  ocular  micrometers  (fig.  34)  have 
naturally  quite  a  different  action.  When 
the  glass  plate  lies  on  the  stage,  the  divi- 
sions and  the  object  are  equally  enlarged  by 
the  entire  dioptrical  apparatus  of  the  instru- 


Fig.  34.  Eye-piecemicrometer. 

in  the  eye-piece,  the  micrometer  is  enlarged 
by  the  weak  ocular  lens  only,  and  appears  to  the  eye  simultaneous- 
ly with  the  image  of  the  object  to  be  measured,  which  is  enlarged 
by  the  objective  and  again  somewhat  diminished  by  the  field 
glass.  This  may  be  accomplished  with  glass  micrometers 
which  are  coarser,  and  therefore  more  accurate,  and  also  less 
expensive  to  construct.  They  do  not  wear  out,  and  any  object 
in  any  position  on  the  slide  may  be  instantaneously  measured, 
so  soon  as  the  eye-piece  containing  the  micrometer  has  been 
substituted  for  the  ordinary  one,  and  adjusted  by  turning  it  in 
the  tube.  But  with  more  opaque  objects  an  inconvenience 
arises  in  the  difficulty  of  seeing  the  micrometer  divisions  over 
the  object  to  be  measured.  No  microscope  should  be  without 
such  a  micrometer,  which  may  be  obtained  for  a  few  (4-5) 
thalers.  In  consequence  of  the  unequal  visual  distances  of 
different  observers,  it  is  necessary  to  vary  the  adjustment  of  the 
ocular  micrometer  by  means  of  a  screw  arrangement,  so  that 
it  and  the  object  may  simultaneously  appear  alike  distinct  to 
any  eye. 

It  should  not  be  forgotten,  in  using  the  eye-piece  micrometer, 
that  its  value  is  a  relative  one,  depending  on  the  strength  of  the 
objective  used  (therefore  variable  with  immersion  lenses),  and 
the  length  of  the  microscope  tube,  which  always  determines  the 
size  of  the  image.  It  is  most  advantageous  to  have  the  latter 
completely  drawn  out  when  measuring. 

We  have  a  very  simple  procedure  for  determining  the  value 
of  the  micrometer  in  the  eye-piece  ;  we  avail  ourselves  of  the 
aid  of  a  glass  micrometer  on  the  stage.  Assuming  that  it  has  a 


APPARATUS    FOE    MEASURING    AND    DRAWING.  37 

Paris  line  divided  into  100  portions  ;  with  the  objective  A,  per- 
haps five  spaces  of  the  eye-piece  micrometer  will  exactly  cover 
one  space  on  the  stage  micrometer ;  the  value  of  one  of  its 
spaces  for  the  objective  A  is  therefore  jfo'".  To  obtain  greater 
accuracy,  various  portions  of  the  stage  micrometer  should  always 
be  used  for  the  measurement,  and  the  mean  of  10-15  single 
measurements  drawn.  Always  keep  in  the  middle  of  the  field 
to  avoid  any  distortion  of  the  image  that  may  be  present.  In 
this  manner  the  value  of  the  eye-piece  micrometer  for  the 
various  objectives  of  a  microscope  is  reckoned  and  tabulated. 

Besides  this  most  simple  eye-piece  micrometer,  serving 
completely  nearly  all  the  purposes  of  measurement,  various 
other  modifications  have  been  produced,  but  we  cannot  at 
present  enter  'into  their  consideration.  Those  who  are  inter- 
ested in  the  subject  may  read  the  respective  section  in  liar- 
ting's  work. 

All  statements  as  to  the  size  of  microscopical  bodies  naturally 
depend  upon  the  unity  of  measure  on  which  they  are  based. 
Microscopists,  as  a  rule,  use  the  measure  in  general  use  in  their 
country ;  those  of  England  use  the  English  inch,  which  is 
divided  into  decimal  and  duodecimal  lines  ;  those  of  France  use 
the  Paris  line  or  the  millimetre.  In  Germany  one  of  the  two 
last  mentioned  unities  of  measure  is  generally  used,  though  the 
Yienna  and  Rhine  lines  are  also  used.  The  Paris  measure  is 
most  convenient,  and  the  millimetre  deserves  the  preference. 
It  is  very  convenient  to  use  the  thousandth  part  of  a  millimetre 
as  a  unity,  under  the  name  of  micromillimetre,  mmm,  as  proposed 
by  Hart  ing. 

A  millimetre  is  0.4433  of  a  Paris  line. 

0.4724  of  an  English  duodecimal  line. 
0.4587  of  a  Rhenish  line. 
0.4555  of  a  Yienna  line. 

The  Paris    line  is  2.2558  millimetres. 
"      English      "     2.1166  " 

"      Rhenish     "     2.1802          " 
"      Yienna       "     2.1952  « 

For  further  comparison  we  give  a  small  table  for  reducing 
Paris  lines  to  millimetres  and  vice  versa. 


38 


SECTION    SECOND. 


Millimetre. 

Paris  lines. 

1. 

= 

0.4433 

0.9 

— 

0.3990 

0.8 

— 

0.3546 

0.7 

— 

0.3103 

0.6 

= 

0.2660 

0.5 

— 

0.2216 

0.4 

— 

0.1773 

0.3 

— 

0.1330 

0.2 

— 

0.0887 

0.1 

— 

0.0443 

0.01 

— 

0.0044 

0.001 

= 

0.0004 

2. 

Paris  lines. 

Millimetres. 

1. 

— 

2.2558 

0.9 

— 

2.0302 

0.8 

^ 

1.8047 

0.7 

— 

1.5791 

0.6 

— 

1.3535 

0.5 

•  — 

1.1279 

0.4 

= 

0.9023 

0.3 

= 

0.6767 

0.2 

— 

0.4512 

0.1 

— 

0.2256 

0.01 

— 

0.0226 

0.001 

— 

0.0023 

The  goniometer  is  an  apparatus  used  for  measuring  the 
angles  of  crystals.  A  simple  and  efficient  arrangement  (fig.  35), 

contrived  by  C.  Schmidt  for  this 
purpose,  consists  of  the  following : 

'   _,  Nr^p^f^S^^t^*^^      —A  circular  plate,  a  b  c,  divided 

into  thirds  of  a  degree,  is  placed 
around  the  (fixed)  microscope 
tube,  at  its  upper  end.  To  the 
outer  edge  of  an  eye-piece  (p\ 
provided  with  a  crossed  thread,  a 
vernier  (d)  is  fastened.  The  angle 
of  the  crystal  to  be  measured  is 

Fig.   35.     C.  Schmidt's  goniometer,     a  5  c. 

graduated  disk ;  d,  nonius  at  the  border  of  brought  tO  the  Centre  Ol  the  CrOSS, 
the  eye-piece  p  ;  e,  lens  for  reading  off.  c 

and  the  threads  are  made  to  cover 

both  sides  of  the  angle  in  succession.  The  extent  which  it  is 
necessary  to  turn  the  eye-piece  in  order  to  effect  this  is  read  off 
at  the  vernier,  above  which  a  plano-convex  lens  (e)  is  placed. 

Drawing  the  investigated  object  is  not  less  important  than  its 
measurement  with  the  microscope.  It  would  appear  to  be 
superfluous  to  speak  further  of  its  value.  It  is,  indeed,  generally 
acknowledged  in  the  study  of  all  branches  of  natural  history, 
and  a  successful  illustration  is  often  much  more  rapidly  com- 
prehended than  the  most  detailed  description. 

Every  one  occupied  with  natural  science,  and  especially  with 
medicine,  should,  therefore,  be  able  to  practise  this  art,  at  least 
in  a  slight  degree.  This  qualification  is  all  the  more  necessary 


APPARATUS    FOR    MEASURING    ANI>    DRAWING.  39 

in  consequence  of  the  peculiar  nature  of  microscopical  vision. 
While  an  object  which  is  perceived  by  the  naked  eye  may  be 
grasped  and  portrayed  by  an  artist  who  is  experienced  in  the 
guidance  of  pencil  and  brush,  seeing  correctly  with  the  micro- 
scope is  itself  an  art  which  must  first  be  learned  before  thinking 
of  making  a  successful  drawing.  Although  the  inquirer  who 
understands  his  specimen,  even  though  no  great  master  of  the 
art  of  drawing,  would  be  able  to  produce  a  tolerable  and  useful 
representation  of  the  object,  this  would  not  be  the  case  with  a 
much  more  proficient  artist  who  ventures,  for  the  first  time,  to 
represent  a  microscopical  image.  Misunderstandings  and  errors 
would  not  be  wanting.  The  latter  is  deficient  in  comprehension, 
while  the  microscopist  is  often  enough  in  the  fatal  position  of 
understanding  his  specimen  thoroughly,  and  yet  not  able,  with 
his  unpractised  hand,  to  reproduce  it  faithfully  or  with  artistic 
conception. 

The  simpler  accessories  for  drawing,  such  as  the  pencil, 
the  rubber,  and  water-colors,  are  generally  sufficient  for  the 
microscopist.  Much  that  one  draws  to  assist  the  memory  during 
an  investigation  has  only  the  character  of  simple  sketches; 
likewise,  many  things  that  are  only  incidentally  noticed,  are 
considered  worthy  of  being  drawn  in  a  note-book.  It  is  not 
advisable  to  draw  everything,  on  account  of  the  great  outlay  of 
time  which  would  be  necessary.  Since  we  have  learned  to 
preserve  specimens  in  fluid,  in  such  a  manner  as  to  retain  their 
natural  appearances,  they  will  render  better  service  during  a  pro- 
longed investigation  than  a  volume  filled  with  simple  sketches. 
One  should  be  particular  in  selecting  drawings  for  publication. 
Not  every  preparation,  not  every  view  is  characteristic.  A  well- 
selected  representation  is  of  more  service  than  a  whole  series  of 
less  pregnant  ones. 

More  explicit  directions  as  to  details  would  here  be  out  of 
place.  Rough  paper  may  be  used  for  the  larger  sketches ;  a 
very  fine  English  drawing-paper  is  necessary  for  the  reproduc- 
tion of  very  delicate  textural  relations.  A  series  of  various 
sorts  of  pencils,  of  the  best  manufacture,  should  be  selected. 
One  should  become  accustomed  to  trace  the  first  outlines  as  deli- 
cately as  possible,  then  proceed  to  the  darker  shades,  and  only  at 


40  SECTION    SECOND. 

last  bring  in  the  strong  shade  lines.  The  greatest  care  should  be 
devoted  to  keeping  the  point  of  the  pencil  in  order,  for  which 
purpose  a  file  is  best,  if  it  be  desirable  to  make  any  approach  to 
the  delicacy  and  fineness  of  many  microscopical  preparations. 
The  use  of  the  rubber  should  be  learned  from  an  expert  teacher, 
thereby  saving  much  consumption  of  time  in  shading.  It  should 
not  be  forgotten  to  lay  in  the  shading  symmetrically  on  the  right 
side,  as  it  is  only  thus  that  elevations  and  depressions  can  be 
brought  forward  in  the  picture.  The  intensity  of  the  same  is  to 
be  kept  carefully  in  mind,  and  rendered  as  faithfully  as  possible, 
as  this  is  the  essential  foundation  of  the  natural  disposition  of 
many  microscopical  appearances. 

In  using  water-colors,  the  more  transparent  ones  are,  as  a  rule, 
employed ;  more  rarely  those  of  a  thicker  consistence.  Their 
application  is  soon  learned.  Too  dazzling  colors  are  not  to  be 
used  ;  one  should  accustom  one's  self  to  make  fine  colored  lines 
with  the  point  of  a  brush,  which,  for  many  purposes,  are  prefer- 
able to  lines  made  with  a  lead  pencil. 

In  the  course  of  time  many  kinds  of  apparatuses  have  been 
invented  for  rendering  assistance  in  making  drawings  from  the 
microscope,  and,  in  fact,  it  is  necessary  for  the  microscopist  to 
have  such  an  appropriately  constructed  arrangement,  especially 
when  laying  out  a  somewhat  complicated  figure,  and  for  accu- 
rately rendering  the  various  relations  of  form  and  size  of  its  con- 
stituent parts. 

All  the  respective  apparatuses  aim,  by  means  of  special  con- 
trivances, to  throw  the  microscopical  image  on  to  a  sheet  of 
paper,  placed  near  the  microscope,  where  its  outlines  may  be 
traced  with  the  point  of  a  pencil. 

Glass  prisms  are  generally  used  for  this  purpose.  The  simple 
drawing  prism  may  be  placed  over  the  eye-piece  by  means 
of  a  ring  which  fits  over  the  tube  of  the  microscope.  It  must 
be  movable  over  the  former  so  that  it  can  be  approached 
towards,  or  removed  farther  from  the  eye-piece.  The  paper 
may  be  placed  on  a  drawing-desk,  similar  to  a  note-desk,  behind 
the  microscope. 

The  camera  lucida  of  Chevalier  and  Oberhauser  is  more  con- 
venient than  the  simple  drawing-prism  for  our  vertical  instru- 


APPARATUS    FOE   MEASURING   AND    DRAWING. 


41 


ments,  but  is  also  somewhat  more  expensive,  costing  from  30  to  50 
francs.  It  consists  of  a  complicated  eye-piece,  which  contains  two 
prisms,  and  causes  a  complete  inversion  of  the  image.  A  glance 
at  fig.  36  will  readily  enable  us  to  comprehend  the  arrangement 
of  this  instrument.  A  tube  A,  bent  at  right  angle,  has  at  d  a 
prism.  In  front  of  it  is  placed  the  eye-piece  B,  with  the  field- 
glass  f  and  the  ocular  lens  e.  At  a  short  distance  from  the 
latter  is  the  small  glass  prism  C,  surrounded  by  a  black  metal 
ring.  The  course  of  the  rays  of  light  is  clear.  They  pass 
through  the  external  prism  to  the  eye  of  the  observer.  The 
latter  sees  not  only  through  the  small  prism,  but  also  through 
the  opening  of  the  ring,  a  paper  placed  beneath,  where  the 
microscopical  image  is  projected,  and  can  be  easily  traced  with 
a  pencil. 


Fig.  36.    Camera  lucida  of  Chevalier  and  OberhSuser.    The  piece  B  is  turned  90°. 

The  camera  lucida,  when  used,  takes  the  place  of  the  eye- 
piece, and  is  fastened  on  to  the  miscroscope  tube  with  the  screw  c. 
The  illumination  must  be  carefully  regulated,  so  that  the  point 
of  the  pencil  may  be  accurately  seen,  which  is  indispensable. 
A  black  pasteboard  screen,  placed  in  front  of  the  drawing- 
paper,  has  a  good  effect. 

The  place  where  the  image  is  received,  that  is,  where  the 


42  SECTION    SECOND. 

paper  lies,  is  naturally  of  importance.  The  farther  from  the 
instrument  this  takes  place,  of  course,  the  larger  it  will  be.  It 
should  be  made  a  rule  to  have  the  drawing-paper  placed  at  as 
nearly  the  same  elevation  with  the  stage  as  possible,  that  is,  about 
25  centimetres  beneath  the  prism.  If  the  magnifying  power  of 
the  objective  and  of  the  camera  lucida  be  ascertained,  by  shorten- 
ing the  microscope  tube  and  raising  the  drawing-desk,  round 
numbers  may  be  obtained,  which  is  certainly  convenient.  The 
camera  lucida,  however,  cannot  readily  be  used  with  advantage 
for  more  than  tracing  the  outlines.  It  is  very  convenient  to  use 
the  knee-shaped  tube  with  the  prism,  after  replacing  its  eye- 
piece with  another,  thus  converting  the  microscope  into  a  hori- 
zontal one,  though  there'  is  a  loss  of  light. 

The  magnifying  power  used  when  drawing  should  always  be 
noted,  preferably  near  the  drawing  in  the  familiar  way  ;  as  %£• 
(20  diameters),  -S-^2-,  -6-f2-,  etc.  It  is  only  practicable  in  a  very 
few  cases  to  draw  everything  with  the  same  enlargement,  as  has 
been  proposed  by  many  persons.  What  pictures  would  often 
result ;  dwarfs  by  the  side  of  giants  ! 

We  can  readily  conceive  that  photography,  that  grand  dis- 
covery of  modern  times,  has  not  been  ignored  by  the  micro- 
scopist ;  its  value  for  giving  a  true  objective  representation  of 
a  microscopic  specimen  must  be  self-evident.  Nevertheless, 
the  number  of  observers  who  have  worked  at  it,  either  for 
themselves  alone  or,  which  has  generally  been  the  case,  in  con- 
nection with  a  professional  photographist,  has  not,  as  yet,  been 
very  considerable.  The  greater  part  have  been  deterred  by  the 
want  of  familiarity  with  the  technology  of  photography,  and 
the  generally  very  much  overrated  difficulties  of  micro-photo- 
graphic manipulation.  What  may  be  thus  accomplished,  what 
a  future  photography  also  has  in  store  for  microscopical  investi- 
gations, is  shown  by  many  examples  of  the  present  time. 

As  early  as  the  year  1845,  Donne,  a  French  observer,  pub- 
lished an  A-ilas  djanato?nie  microscopique,  the  illustrations  for 
which  were  copied  from  those  taken  on  Daguerre's  metal  plate 
by  means  of  the  sun-microscope.  In  more  recent  times  an  im- 
mense progress  has  been  made  in  photography  by  taking  the 
.negative  011  a  glass  plate  covered  with  iodized  collodion.  We 


APPARATUS    FOR   MEASURING    AND    DRAWING.  43 

have  received  from  Paris  many  beautiful  micro-photographs, 
which  were  taken,  in  part,  with  very  high  powers.  "Within  a 
few  years  Hessling  and  Kollmann,  in  connection  with  Albert, 
the  renowned  photographer  of  Munich,  have  commenced  the 
publication  of  a  folio  of  photographs  deserving,  in  every 
respect,  the  highest  encomiums.  Unfortunately,  it  remains  un- 
completed. Professor  Gerlach,  of  Erlangen,  whom  we  have  to 
thank  for  a  number  of  valuable  contributions  to  microscopical 
technology,  has  published  a  small  but  interesting  guide  to  mi- 
cro-photographic manipulation.  (Die  Photographic  als  Hiilfs- 
mittel  mikroskopischer  Forschung.  Leipzig,  1862.)  Beale 
and  Moitessier  have  more  recently  treated  of  the  same  theme 
in  a  very  thorough  manner.  B.  Benecke  published  Moitessier's 
work,  enriched  by  many  additions  of  his  own,  in  the  German 
in  1868.  (Die  Photographic  als  Hiilfsmittel  mikroskopischer 
Forschung.  Braunschweig.)  It  is  the  best  work  that  we  have  on 
this  subject  at  the  present  time. 

The  ordinary  compound  microscope  may  be  readily  and,  as 
Gerlach  informs  us,  with  very  slight  outlay  of  money,  turned 
into  a  micro-photographic  apparatus  working  with  sunlight, 
(fig.  37). 

Concentrated  parallel  light,  which  is  afforded  by  the  con- 
cave mirror  (q}  in  connection  with  a  plano-convex  condensing 
lens,  is  used  for  the  illumination.  Cylindrical  diaphragms  with 
small  apertures  are  to  be  used  with  the  stronger  powers.  The 
ordinary  objectives  are  used,  but  they  must  be  scrupulously 
cleaned  before  taking  the  impression,  as  every  particle  of  dust 
will  cause  a  spot  on  the  negative.  The  eye-piece  is  to  be  re- 
moved and  the  photographic  apparatus  placed  on  the  tube  of  the 
microscope  and  held  by  a  ring  (i).  A  tube  (g)  supports  a  wooden 
case  (d),  in  the  upper  end  (c)  of  which  the  sensitive  glass  plate 
may  be  introduced  (at  J).  It  is  better  that  the  wooden  frame 
(£)  of  the  focussing  screen  should  contain  paper,  rendered  trans- 
parent by  oiling  instead  of  the  ground-glass  plate  of  the  ordi- 
nary apparatus.  The  usual  black  cloth,  thrown  over  the  head, 
serves  to  darken  the  same  while  focussing ;  the  cone  (a)  on  the 
chest  contains  a  magnifying  glass,  to  permit  of  the  most  accurate 
focussing.  In  order  that  the  weight  of  the  chest  may  not  de- 


44 


SECTION   SECOND. 


press  the  microscope  tube  (a)  in  its  sheath  (???),  a  ring  (I)  sur- 
rounds the  latter,  and  may  be  tightened  by  means  of  the 
Bcrew  (k).  The  brass  capsule  which  covers  the  objectives  of 
the  ordinary  apparatus  is  replaced  by  a  black,  horizontal  tablet, 


Fig.  37.  Gerlach's  micro-photographic  apparatus :  a  hollow  cone,  to  be  placed  on  6,  the  focus- 
sing screen  ;  c  projection  at  the  upper  part  of  the  case  d  ;  e  metal  ring  at  its  bottom ;  /  metal 
ring  at  the  upper  part  of  the  wooden  tnUe  g  ;  h  metal  plate  at  the  lower  end  of  the  same  ;  i  ring 
at  the  upper  end  of  the  metallic  tube ;  A:  screw  of  the  metal  ring  Z,  which  serves  to  clamp  the 
spring  sheath  m ;  n  tube  of  the  microscope  with  the  objectives  ;  o  stage  ;  p  the  metallic  cylinder 
for  carrying  the  diaphragm  and  illuminating  lens;  q  the  mirror;  r  the  metallic  bar  which 
supports  the  sta<£e  ;  «  the  horse-shoe  foot ;  t  the  micrometer  screw. 

which  may  be  placed  between  the  mirror  (<?)  and  the  condens- 
ing lens  (p). 

That  this  apparatus,  afterwards  still  further  improved  by  the 
inventor,  suffices  for  obtaining  excellent  representations,  may  be 
learned  from  Gerlach's  beautiful  photographs.  However,  it  is 


APPARATUS    FOE    MEASURING    AND    DRAWING. 


45 


still  of  a  somewhat  primitive  character,  and  has  many  defects. 
The  illumination  is  not  sufficient  for  strong  magnifying  powers, 
and,  as  the  length  of  the  tube  is  unalterable,  the  magnifying 
power  of  an  objective  cannot  be  changed.  The  tube  of  the 
microscope  is  too  heavily  loaded,  which  restricts  and  endangers 
the  working  of  the  micrometer  screw. 

o 

A  similar,  but   improved  arrangement  of    Moitessier's   ap- 
pears, therefore,  to  be  more  suitable  (fig.  38). 

A  folding  camera  (B)  is  supported  by  a  strong  three-legged 
wooden  stand  (A),  which 
rests  on  a  small  table.  The 
camera,  like  the  bellows  of 
an  accordion,  is  capable  of 
being  lengthened  or  short- 
ened, so  that  the  impression 
may  be  taken  at  various  dis- 
tances from  the  objective. 
A  sheet  of  white  paper, 
stretched  in  the  frame  (D), 
which  may  be  seen  from 
beneath  at  the  side,  when  the 
door  is  open,  takes  the  place 
of  the  usual  ground-glass 
plate,  which,  as  I  know  from 
personal  experience,  renders 
the  accurate  adjustment  of 
the  focus  very  difficult.  The 
tube  of  the  microscope  pro- 
jects freely  into  the  camera, 
through  the  opening  in  its 
bottom.  This  aperture  should 
fit  closely  around  the  tube. 

mi        .,,          .        ,.          .        ,  ,     .        ,     Fig.  88.    Moitessier's  Apparatus.    A  Pillars  of 
JLlie   illumination  IS  Obtained       the  f  olding  camera  B;  Cits  door;  D  frame. 

from  a  silvered  mirror  and  a  condensing  lens,  both  of  which 
play  through  a  sliding  arrangement  on  a  horizontal  wooden 
ledge.  The  light  from  the  mirror  is  concentrated  by  the  lens 
on  to  the  mirror  of  the  microscope,  into  the  stage  of  which  an 
achromatic  condenser  is  to  be  inserted. 


46  SECTION    SECOND. 

Another  arrangement  (fig.  39)  appears  to  be  still  more  effi- 
cient, although  it  can  only  be  accomplished  with  a  microscope 
which  is  capable  of  assuming  a  horizontal  position.  The  re- 
moval of  the  mirror  from  the  microscope  permits  of  the  employ- 
ment of  direct  sunlight.  The  illumination  is  obtained  from  the 
silvered  mirror  II,  the  diaphragm  F,  the  convex  lens  E,  and  a 
plate  of  very  delicate  ground  glass  D,  which  are  placed  in  a 
sliding  arrangement.  The  ground-glass  plate  should  have  such 
a  position  that  a  small  circle  of  light  will  be  thrown  on  it. 


Fig.  39.  Horizontal  apparatus.  A  folding  camera,  B  microscope ;  C  achromatic  condenser ; 
M  the  mirror  of  the  microscope  turned  aside  ;  H  the  silvered  mirror ;  F  the  diaphragm  ;  E  con- 
vex lens ;  D  ground-glass  plate. 

A  temperature  of  14-18°  R.  is  best  suited  for  taking  the  im- 
pression. Natural  light  is  used  to  produce  the  photographic 
picture.  The  duration  of  the  exposure,  naturally  varying 
according  to  the  intensity  of  the  light,  increases  with  the  strength 
of  the  magnifying  power  employed,  and  with  full  sunlight  lies, 
according  to  Geiiach's  observations,  between  five  seconds  for  a 
magnifying  power  of  5-25  diameters,  and  40  seconds  for  one 
of  250-300  diameters.  Among  the  methods  of  artificial  illu- 
mination, that  with  magnesium  light  deserves  mention  above 
all  others.  A  photogenic  lamp,  together  with  some  additional 
contrivances,  also  affords  good  illumination  (S.  T.  Stein).  The 


APPARATUS    FOR    MEASURING    AND    DRAWING.          47 

duration  of  the  exposure  depends  on  the  manner  of  treating  the 
sensitive  glass  plate.  The  wet  method  with  collodium  requires 
the  shortest  time ;  the  dry  method  and  that  with  albumen  re- 
quire a  much  longer  time. 

Gerlach,  Beale,  Moitessier,  and  Benecke  have  entered  fully 
into  all  the  remaining  details  of  the  process.  The  limits  of  our 
little  wrork  prevent  us  from  noticing  the  subject  further,  and  we 
must  therefore  refer  to  those  authorities. 

It  is  self-evident  that  the  trouble  of  photographing  should 
only  be  bestowed  on  preparations  which  are  irreproachable  and 
free  from  every  contamination.  It  is  important  to  have  but  a 
small  number  of  bodies  in  the  field ;  for  example,  only  a  few 
blood-corpuscles,  or  a  few  epithelial  cells.  Compact  tissues  re- 
quire the  thinnest  sections.  Pale-bordered  objects  require 
stronger  shading.  Therefore,  Canada  balsam  preparations  are 
less  suitable,  as  are  also  objects  mounted  in  glycerine,  though 
some  assistance  may  be  rendered  in  such  cases  by  tinging  them 
with  carmine.  Preparations  injected  with  carmine  or  Prussian 
blue  afford  admirable  pictures,  and  Gerlach  has  reproduced 
them  even  with  a  repetition  of  their  colors ! 

If  a  micrometer  of  known  value  is  photographed  at  the  same 
time  and  with  the  same  enlargement,  the  size  of  the  object  rep- 
resented may  be  ascertained  by  measurement  with  a  pair  of 
compasses  with  exceeding  facility  and  accuracy. 

Such  micro-photographs  are  less  adapted  for  furnishing  large 
works  to  be  issued  in  large  numbers,  as  a  certain  inequality  of 
the  positive  prints  is  unavoidable.  They  are  admirable,  on  the 
contrary,  for  purposes  of  instruction.  Judging  from  the  photo- 
graphs we  have  seen  of  microscopic  objects,  we  must  doubt 
wl*ether  such  photographs  as  are  now  made  will  be  useful  for 
deciding  subtle  questions  of  texture.  Only  a  few  French  and 
American  representations  of  diatomacese  make  an  exception. 

In  recent  times,  as  is  well  known,  such  extraordinarily  small 
photographs  have  been  produced,  that  the  picture  can  only  be 
recognized  with  a  strong  magnifying  glass  or  a  microscope. 
Here  the  silver  precipitate  is  of  such  fineness  that  a  considerable 
magnifying  power  is  necessary  to  render  it  visible. 

These  minimal  photographs  have  led  Gerlach  to  make  a  pecu- 


48  SECTION    §ECOND. 

liar  application  of  photography  to  microscopical  purposes ;  to 
an  increase  of  the  enlargement  by  photographic  means. 

The  first  negative  of  an  object  obtained  by  means  of  the  mi- 
croscope is  hereby  subjected  to  a  new  enlargement.  A  second 
negative  is  thus  obtained,  which  presents  light  and  shadow  in 
the  same  manner  as  the  object,  and  therefore  cannot  be  con- 
verted into  a  useful  positive  image.  This  is  quite  possible,  how- 
ever, when  the  second  negative  is  exposed  to  a  new  enlargement 
and  the  tertiary  is  thus  obtained,  which  corresponds  to  the  light 
and  shadow  of  the  first  one.  The  enlargement  may  be  increased 
till  the  silver  precipitate  becomes  visible.  By  diluting  the  pho- 
tographic solutions,  as  well  as  by  a  peculiar  treatment  of  the 
sensitive  glass  plate,  this  visibility  may  be  very  much  deferred. 
In  Gerlach's  work  three  such  photographs  of  the  scale  of  a  but- 
terfly (Papilio  Janira)  by  265,  670,  and  1,460  fold  enlargement 
may  be  found.  Parisian  and  North  American  photographs  of 
the  pleurosigma  angulatum,  which  I  have  obtained  through 
Lackerbauer  and  Woodward,  show  the  hexagonal  areolations 
very  beautifully,  enlarged  to  2,000  and  2,500  diameters.  Im- 
pressions of  the  latter  with  19,050  fold  enlargement  I  certainly 
do  not  comprehend.  It  remains  for  the  future  to  show  what 
practical  advantages  such  applications  of  the  micro-photographic 
apparatus  may  present,  that  is,  how  far  structural  relations, 
which  by  the  first  impression  are  not  recognizable  by  the  eye, 
can  be  made  visible  by  the  following  ones. 


0cction 


THE  BINOCULAR,  THE  STEREOSCOPIC,  AND  THE  POLARIZING 

MICROSCOPE. 

THE  idea  of  producing  microscopes  through  which  several 
persons  are  able  to  observe  simultaneously  one  and  the  same  ob- 
ject is  sufficiently  obvious,  and,  without  doubt,  such  instruments 
must  be  very  convenient  for  a  teacher  in  his  demonstrations. 

By  the  application  of  prisms  over  the  objective,  the  rays  of 
light  which  pass  through  it  may  be  divided  into  two,  three,  four 
bundles.  This  is  accomplished  either  by  dioptrical  means, 
through  an  achromatic  compound  prism  (fig.  40),  or  by  catop- 
trical,  by  total  reflection,  as,  for  instance,  the  prism  combination 
shown  in  fig.  41.  If  several  microscope  tubes,  each  provided 


Fig.  40. 


Fig.  41. 


with  its  own  eye-piece,  and  corresponding  to  the  number  of 
bundles  into  which  the  rays  are  divided,  be  placed  over  the 
prism,  it  will  be  possible  for  a  number  of  persons  to  observe 
simultaneously.  The  eye-piece  must  be  movable  in  its  tube,  by 
means  of  a  screw,  to  permit  of  individual  focussing. 


50 


SECTION   THIRD. 


The  division  of  the  rays  which  have  passed  the  objective  into 
two,  three,  or  four  bundles,  is  naturally  combined  with  a  corre- 
sponding diminution  of  the  intensity  of  the  light ;  there  is  also 
some  loss  of  light  in  the  prisms.  Only  the  weaker  objectives 
can  therefore  be  employed  with  such  multocular  microscopes, 
as  they  have  been  called,  and  the  images  leave,  as  a  rule,  much 
to  be  desired.  Such  binocular,  triocular,  and  quadrocular  mi- 
croscopes have  recently  been  constructed  and  brought  into  com- 
merce, especially  by  Nachet,  of  Paris. 


Fig.  42.    "Wenham's  arrangement  of  the  stereoscopic  microscope. 

The  binocular  microscope  may  also  be  so  constructed  that 
its  two  tubes  can  be  used  for  both  eyes  of  one  and  the  same  ob- 
server. When  they  are  so  placed  as  to  correspond  to  the  con- 
vergence of  the  optic  axes,  the  two  images  cover  each  other,  and 
the  consequence  must  necessarily  be  that  the  object  no  longer 
seems  flattened,  but  assumes  a  corporeal  appearance.  In  this 
manner  is  constructed  the  stereoscopic  microscope,  the  only 
efficient  application  of  the  binocular  principle.  We  have  to 


THE   BIlSrOCULAE,    ETC.,    MICROSCOPE. 


51 


thank  Riddell,  an  American,  for  the  production  of  the  first 
instrument  of  this  kind.  Since  that  time,  English  opticians 
especially,  such  as  the  firm  of  Ross  &  Co.,  of  London,  have, 
with  a  certain  predilection,  constructed  these  microscopes,  and 
have  contrived  arrangements  by  means  of  which  ordinary  micro- 
scopes may  be  readily  converted  into  stereoscopic  instruments. 
Wenham's  very  excellent  arrangement,  in  general  use  there  at 
present,  is  represented  by  our  fig.  42.  With  the  main  tube  A  1 
of  the  instrument  is  movably  connected — that  is,  capable  of 
being  approximated  towards,  or  separated  from  it — the  secondary 
tube  2.  A  small  prism  a  projects 
as  far  as  the  optical  axis  of  the 
tube  1 ;  its  f  orai  may  be  recognized 
more  accurately  in  the  enlarged 
drawing  B.  Each  bundle  of  rays 
is  so  divided,  after  its  passage 

Jt  O 

through  the  objective,  that  the  one 
passes  unbroken  through  the  tube 
1,  the  other  through  the  prism  B, 
in  the  direction  al)cd,  into  the  sec- 
ondary tube  2.  Nachet  has  also, 
for  years,  supplied  such  stereo- 
scopic microscopes ;  likewise  Hart- 
nack,  whose  stereoscopic  eye-piece 
is  represented  by  our  fig.  4A. 
Opinions  are  divided  with  regard 
to  the  utility  of  these  instruments ; 
they  have  certainly  been  over-esti- 
mated by  many.  We  must  leave 
it  for  the  future  to  decide  whether  science  is  to  derive  any 
benefit  from  them.  As  examples,  we  have  represented  in  onr 
fig.  43  such  an  instrument  by  II.  and  W.  Crouch,  of  London,  and 
in  fig.  45  one  by  Nachet. 

The  examination  of  tissues  by  polarized  light  has,  on  the 
contrary,  a  high  scientific  value,  as,  by  this  means,  molecular 
relations  become  evident  which,  by  investigation  with  ordinary 
light,  remain  entirely  concealed.  The  interpretation  of  what  is 
seen  is,  in  many  cases,  difficult,  and  generally  lies  within  the  pro- 


Fig.  43.  Crouch'*  stereoscopic 
microscope. 


52 


SECTION   THIRD. 


vince  of  optics,  with  which  the  medical  observer  is  usually  but 
little  familiar. 

Every  ordinary  instrument  may  be  changed  to  a  polarizing 
microscope,   in   a  very   simple   manner,  by   adding    to    it   a 
polarizer  and  an  analyzer.     For  this  purpose  Nicol's  prisms, 
consisting   of   double  refracting   calcareous 
Iceland  spar,  are  used.     They  are  so  con- 
structed as  to  transmit  only  one  of  the  two 
rays  into  which  a  beam  of  ordinary  light  is 
made  to  separate  on  passing  through  this 
substance,  while  the  other  is  lost  by  reflec- 
tion. 

The  polarizer  is  placed  close  beneath 
the  object,  preferably  in  the  opening  of 
the  stage  with  the  addition  of  a  convex  Jens 
(fig.  46).  The  analyzer,  on  the  contrary, 
receives  various,  and  by  no  means  equally 
good  positions.  As  a  rule,  it  is  placed  by 
the  opticians  over  the  objective  in  the  tube 
of  the  microscope ;  an  arrangement,  however, 
which  causes  too  great  loss  of  light,  which 
becomes  very  unpleasant  in  investigations 
where  the  double  refraction  is  weak.  It  is 
much  more  advantageous  to  place  the  analyzer  over  the  eye- 
piece, enclosed  in  a  metallic  tube.  Although  by  this  means  the 
field  is  extraordinarily  diminished,  especially  when  the  Nicol 
is  small,  it  presents  much  more  light  than  the  larger  field 
obtained  by  the  first-mentioned  arrangement.  Ilartnack  has 
recently  placed  a  plano-convex  flint-glass  lens  of  short  focal  dis- 
tance (fig.  46,  a)  over  the  polarizer.  The  analyzer  (fig.  47)  he 
has  placed  in  the  eye-piece  (&)  and  the  latter  is  made  to  rotate 
within  a  graduated  disk  (a).  By  this  means  he  has  essentially 
increased  the  efficiency  of  his  polarizing  apparatus. 

The  two  Nicols  are  to  be,  at  first,  so  arranged  that  their  pola- 
rizing planes  are  parallel  to  each  other,  which  gives  an  illumi- 
nated field.  This  cannot  be  made  too  intensely  bright,  especially 
with  weak  double  refraction.  A  condenser,  such  as  we  have 
mentioned  alove,  placed  over  the  polarizing  calcareous  spar 


Fig.  44.  Hartnack's 
stereoscopic  eye-piece. 
The  t\vo  tubes  b  may  be 
adjusted  according  to  ne- 
cessity by  means  of  the 
button  c  ,•  a  for  insertion 
into  the  tube  of  the  mi- 
croscope. 


THE   BESTOCULAK,    ETC.,    MICROSCOPE. 


53 


prism,  is  very  serviceable,  as  was  pointed  out  years  ago  by  H. 
von  Molil. 

"When  the  polarizing  planes  are  placed  at  right  angles  to  each 
other,  by  turning  the  analyzer  90°,  the  field  is  darkened  (it 
should  appear  entirely  dark  with  a  good  apparatus),  and  doubly 
refracting  bodies  appear  either  illuminated  or  in  colors. 


Fig.  45.    Nachcfs  stereoscopic  microscope. 


Fig.  46.  Polarizer.  The 
tube  a  fitted  into  the  stage ; 
6  convex  leas  of  flint  glass. 


Fig.  47.  Hartnack's  ana- 
lyzer, new  construction. 
The  eye-piece  b  c  turns  in  a 
eheath,  which  is  to  be  fas- 
tened to  the  microscope  by 
means  of  the  screw  at  the 
right ;  it  also  has  a  prradu- 
ated  circle  a  ;  a  vernier. 


The  rotation  is  made  in  various  ways:  either  the  analyzer 
placed  upon  or  within  the  eye-piece  is  rotated,  or  the  stage  is 
rotated,  if  capable  of  that  motion.  When  the  stage  is  immov- 
able and  the  analyzing  prism  is  placed  within  the  tube  over  the 
objective,  the  opticians  introduce  an  especial  mechanism,  by 
means  of  which  it  may  be  rotated  in  its  sheath. 

The  objects  to  be  investigated  should  be  made  as  transparent 


54  SECTION   THIED. 

as  possible,  when  the  recognition  of  weak  double  refraction  is  in 
question.  Mounting  with  Canada  balsam,  which  would  per- 
haps render  the  object  so  transparent  as  to  be  totally  unservice- 
able for  the  ordinary  methods  of  examination,  would  here  render, 
excellent  service. 

In  delicate  investigations,  the  incident  rays  of  light  must  be 
carefully  excluded,  by  placing  a  hood  over  the  stage. 

Thin  scales  of  selenite  or  mica,  of  various  thickness,  placed 
over  the  polarizer,  are  the  means  generally  used  for  developing  a 
lively  play  of  colors  with  polarized  light,  and  for  deciding  as  to 
the  character  of  double  refracting  animal  tissues.  They  are 
examined  at  an  angle  of  45°.  A  film  of  selenite  produces  more 
lively  colors  than  one  of  mica.  In  using  these  plates,  it  is  pre- 
ferable to  have  them  of  the  thickness  which  gives  a  red  of  the 
first  order.  At  the  same  time,  the  sharpness  of  the  microscopic 
polarizing  apparatus  may  also  be  increased  by  the  introduction 
of  a  film  of  such  thinness  as  not  to  cause  any  coloring  of  the 
field. 


Section   jFourtl), 

TESTING  THE  MICROSCOPE. 

IN  testing  and  critically  examining  the  optical  performances 
of  a  microscope,  with  which,  naturally,  the  extent  of  its  mag- 
nifying power  must  also  be  included,  a  number  of  things  have 
to  be  taken  into  consideration ;  and  when  the  appreciation  of 
very  fine  distinctions,  especially  with  the  stronger  objectives,  is 
concerned,  it  becomes  a  difficult  business. 

To  ascertain  the  magnifying  power  of  a  microscope,  the  focal 
length  of  the  objective  and  that  of  the  lenses  composing  the 
eye-piece  may  be  measured,  and  from  this  the  enlargement 
reckoned.  This  subject  is  further  elucidated  in  the  text-books 
on  physics. 

It  is  much  more  convenient,  however,  to  measure  directly 
the  joint  magnifying  power  of  the  several  combinations. 

For  this  purpose,  an  ordinary  glass  stage-micrometer  with 
fine  divisions  is  used ;  a  rule  is  also  placed  on  the  stage.  By 
means  of  the  power  of  double  vision,  which,  however,  requires 
practice,  that  the  head  and  eyeball  may  be  kept  quiet,  the 
image  of  the  micrometer  divisions  will  be  seen  projected  on  to 
the  rule  which  lies  on  the  stage,  and  the  relative  size  of  their 
spaces  may  be  thus  compared.  Granted  the  rule  is  divided  into 
millimetres,  and  that  the  micrometer  has  one  such  millimetre 
divided  into  100  parts.  Two  of  the  divisions  of  the  rule  are 
covered  by  one  space  of  the  micrometer  image.  The  magni- 
fying power  of  the  microscopic  combination  measured  is,  there- 
fore, 200-fold. 

The  distance  of  the  eye-piece  from  the  stage  must  also  be 
taken  into  consideration  in  order  to  obtain  a  precise  expression, 
corresponding  to  the  visual  distance  accepted  as  the  normal 
medium,  which  is,  as  was  already  remarked,  from  8  to  10 


56  SECTION   FOUETH. 

inches,  or  25  centimetres.  Let  us  accept  the  latter  as  the  visual 
distance.  If  now,  for  example,  the  distance  between  the  image 
and  the  eye  over  the  eye-piece  is  20  centimetres,  the  magnify- 
ing power,  with  a  visual  distance  of  25  centimetres,  would  be 
250-fold. 

It  is  necessary  to  determine  in  this  manner  the  magnifying 
power  of  the  various  eye-pieces  with  one  and  the  same  ob- 
jective. It  is  then  only  necessary  to  obtain  the  magnifying 
power  of  each  of  the  remaining  objectives  with  one  of  the  eye- 
pieces,— for  instance,  the  weakest  one, — to  find  by  calculation 
that  of  the  others. 

In  making  this  measurement,  only  those  divisions  lying  in 
the  middle  of  the  field  should  be  used,  to  avoid  any  incidental 
distortion  of  the  image. 

The  image  of  the  micrometer  projected  on  to  the  stage  may 
be  readily  measured  with  the  points  of  the  compasses,  and  its 
size  determined  with  the  rule. 

It  is  also  convenient  to  employ  the  various  projecting  appa- 
ratuses, especially  prisms  on  the  eye-piece. 

Every  serviceable  modern  instrument  should  have  received 
a  careful  correction  of  the  spherical  aberration  of  its  lenses. 
Various  means  have  been  used  for  testing  this.  They  are  more 
fully  treated  of  in  the  larger  works  on  the  microscope  by  Mohl 
and  Harting.  A  slide  thickly  smeared  with  India  ink,  in  which 
small  circles  or  other  figures  are  scratched  with  the  point  of  a 
fine  needle,  may  be  recommended,  when  it  is  desirable  to  make 
a  few  rapid  tests  of  the  lenses.  If  the  instrument  is  adjusted 
with  transmitted  light  for  such  a  circle,  it  should  appear  sharply 
cut  on  the  black  ground,  and  not  surrounded  by  a  halo  of  light. 
If  the  circle  is  then  brought  out  of  focus,  it  gradually  enlarges, 
while  its  sharp  borders  disappear,  without  spreading  a  strong 
halo  of  light  either  inwards  or  outwards  over  the  black  field. 

Secondly,  adequate  correction  of  the  chromatic  aberration 
should  be  observed.  This  cannot  be  complete,  because  there  is 
no  means  by  which  the  secondary  spectrum  can  be  removed. 
Therefore,  reference  is  here  made  only  to  a  correction  which  is 
as  complete  as  practicable.  Modern  objectives  are,  for  the 
most  part,  over-corrected  with  regard  to  chromatic  aberration, 


TESTING    THE    MICROSCOPE. 


57 


and  show  a  bluish  border.  Under-corrected  lenses  present, 
under  the  same  conditions,  a  reddish  margin,  which  is  less 
agreeable  to  the  eye,  though  the  sharpness  of  the  image  remains 
the  same. 

The  flatness  of  the  field  is  of  great  importance  to  the  advan- 
tageous use  of  the  instrument.  Here,  as  we  have  already  found, 
two  tilings  are  to  be  separately  considered,  namely,  the  incur- 
vation of  the  field,  and  the  distortion  of  the  image. 

If  we  strew  a  very  fine  powder  over  a 

a  flat  plate  of  glass,  we  should,  if  the 
field  is  flat,  be  able  to  see  the  molecules 
at  the  centre  and  at  the  periphery  equally 
distinct  and  simultaneously.  If  there  is 
any  incurvation  present,  deeper  focus- 
sing is  requisite  to  see  the  molecules  at 
the  periphery  of  the  field. 

A  glass  micrometer  divided  into  qua- 
dratic fields,  placed  on  the  stage,  should 
appear  as  fig.  48  a,  if  the  image  is  not 
distorted  ;  while,  on  the  contrary,  if  any 
distortion  is  present,  the  squares  assume 
the  appearances  represented  in  our 
figure  at  5  and  <?,  according  as  the  en- 
largement from  within  outwards  in- 
creases or  diminishes. 

If  restrained  by  purely  practical  con- 
siderations in  testing  a  microscope, 
regard  must  always  be  paid,  in  decid- 
ing on  the  merits  of  an  objective,  to  the 
purpose  for  which  the  optician  lias  con- 
structed it ;  whether  for  incident  light 
or  for  light  reflected  from  the  mirror; 
and,  wrheii  the  latter  is  the  case,  whether 
for  central  or  oblique  illumination.  An 


Fig.  48.   Quadratic  glass  mi- 
crometer. 


objective  may,  for  example,  perform 
very  well  with  the  latter,  and  yet  be  very  indifferent  with 
central  illumination ;  inversely,  many  opticians  construct  ob- 
jectives which  are  very  good  in  the  latter  regard,  but  are 


58  SECTION   FOUKTH. 

defective  with  oblique  illumination.  It  is  quite  impossible  to 
construct  a  combination  which  will  be  equally  serviceable  for 
all  the  different  requirements,  resting,  in  part,  on  opposite  physi- 
cal conditions.  The  testing  of  an  objective  should,  therefore, 
never  be  restricted  to  the  use  of  a  single  test  object. 

Two  attributes  may  be  distinguished  in  an  object  glass  ;  first, 
its  defining,  and  second,  its  penetrating  or  resolving  power. 
Mohl  was  right  in  saying  that  on  the  first  depends  the  distinct 
recognition  of  the  outlines  and  forms  of  bodies  ;  on  the  latter, 
the  appreciation  of  its  finer  structure. 

1.  The  defining  power  of  an  objective  depends  upon  the 
complete  correction  of  its  spherical  and  chromatic  aberration. 
Such  an  attribute,  and  of  adequate  extent,  must  be  expected 
from  every  superior  modern  objective,  for  whatsoever  purpose 
it  may  have  been  constructed.     Good  definition  may  be  more 
easily  obtained  with  lenses  of  small  or  moderate  than  with  lenses 
of  larger  angles  of  aperture ;  and  by  aiming  to  extend  the 
aperture,  the  perfection  of  the  definition  is  not  unfrequently 
impaired. 

A  certain  amount  of  practice  is  necessary  to  recognize  a  good 
defining  objective.  The  outlines  of  the  image  obtained  by  it 
appear  fine  and  sharp  ;  objects  lying  near  each  other,  and  those 
which  are  pushed  over  each  other  in  the  same  optical  plane, 
show  their  individual  outlines  distinctly  and  may  be  readily  ap- 
preciated ;  the  entire  image  has  something  clear  and  elegant 
about  it,  like  a  good  copper  plate  or  a  print  with  sharp  letters. 
To  recognize  the  opposite  condition,  it  is  only  necessary  to 
furnish  the  microscope  with  a  pretty  strong  eye-piece.  Thick, 
confused  contours  and  diminished  distinctness  of  the  image 
would  be  met  by  the  observer  ;  the  whole  would  appear  like  a 
print  with  dull,  disconnected  letters.  It  is  just  this  sharpness 
and  neatness  of  the  image  which  at  first  prepossesses  one  in 
favor  of  such  an  objective,  whereas  an  objective  with  greater 
penetrating  power  usually  gives  paler,  more  milky  images,  and 
only  unfolds  its  high  superiority  to  the  connoisseur. 

The  best  defining  objectives  are  a  prime  necessity  for  all  mi- 
croscopes intended  for  scientific  work. 

2.  The  penetrating  or  resolving  power  of  an  objective  depends 


TESTING    THE   MICROSCOPE.  59 

on  its  capability  of  bringing  the  very  fine  details  of  the  surface 
and  interior  of  an  object  into  view.  Its  perfection  has  become 
the  aim  and  the  pride  of  the  microscope-makers  of  the  present 
day,  and  to  it  is  due,  in  a  great  measure,  the  calling  into  existence 
of  the  superior  objectives  of  modern  times. 

The  resolving  power  of  a  combination  depends,  however,  on 
the  extent  of  the  angle  of  aperture,  and,  consequently,  on  the 
obliquity  of  the  rays  of  light  which  the  system  is  capable  of  re- 
ceiving from  the  various  points  of  the  surface  of  an  object.  In 
regarding  a  transparent  surface  containing  lines  placed  close  to 
each  other,  whether  these  appearances  be  due  to  elevations  or  to 
furrows,  we  are  made  to  appreciate  the  value  of  oblique  illumi- 
nation. It  is  clear  that  rays  of  light  which  are  transmitted  axially 
through  the  object  would  yield  less  information  with  regard  to 
such  inequalities  than  those  which  fall  on  its  surface  obliquely. 
Thus,  by  means  of  objectives  of  medium  power,  but  with  con- 
siderable angles  of  aperture,  one  may  see  with  oblique  illumina- 
tion things  of  which  no  trace  can  be  recognized  with  central 
illumination.  An  object-glass  of  very  wide  aperture,  however, 
will  receive,  even  with  ordinary  illumination,  so  many  rays  of 
great  obliquity  that  the  same  kind  of  effect  will  be  produced  as 
by  oblique  illumination  with  an  objective  of  smaller  aperture  ; 
but  when  with  such  an  objective  oblique  illumination  is  used,  a 
greater  resolving  power  is  obtained  than  any  combination  of 
smaller  angular  aperture  can  possess. 

It  will  be  appreciable,  from  the  remarks  which  have  just  been 
made,  why  it  is  just  this  enlargement  of  the  angle  of  aperture 
which  has  been,  of  late,  the  chief  aim  of  the  optician. 

Thus  we  see  that  older  instruments  have  only  the  slight 
angle  of  50°  or  70°  in  their  strongest  systems.  But,  even  as 
early  as  the  year  1851,  the  renowned  London  house  of  Andrew 
Ross  had  given  their  strongest  systems  an  aperture  of  107°  and 
135°,  a  few  years  later  155°.  But  the  limit  was  not  yet 
reached;  for  more  recently  apertures  of  160,  170,  and  even 
176°  have  been  obtained,  in  which  the  actually  available  por- 
tion remained  at  about  130  to  146°. 

Such  objectives  are  of  the  greatest  value  when  penetra- 
ting power  is  required  ;  but  the  defining  power  is  usually 


60  SECTION   FOURTH. 

relatively  greater  with  a  combination  having  a  smaller  angle 
of  aperture. 

^  f  "We  have  already  (p.  19)  mentioned 

R          /ra  I9L        ^e  ilin<uence  which  the  thickness  of 

jJLJm       *ne  covering  glass  exerts  on  the  sharp- 
ness of  the  microscopic  image.     It  is 
customary  to  combine  with  all  of  the 
stronger  objectives  the  apparatus  for 
Fig.  40.  objective  with  correcting  correction,  fig.  49,  which  was  spoken 
^SS^-SSSS&fS^i  of  in  a  preceding  section,  so  that  the 

represent          ^^      ^^    ^Q     broug]lt     nearer      ^ 

gether  or  moved  farther  apart,  as  necessity  may  require,  accord- 
ing to  the  thickness  of  the  covers  used.  Some  of  these  objec- 
tives are  only  to  be  used  dry,  that  is,  with  a  stratum  of  air 
between  the  upper  surface  of  the  glass  cover  and  the  lower 
surface  of  the  lower  lens ;  others,  only  with  a  stratum  of  water 
in  the  place  of  the  stratum  of  air,  and  are  then  called  immer- 
sion lenses.  Other  modern  combinations  can,  however,  be 
used  in  both  media. 

These  immersion  lenses  are  properly  greeted  as  a  great 
advancement,  and  Hartnack,  of  Paris,  has  obtained  a  brilliant 
reputation  within  a  few  years  by  producing  excellent  combi- 
nations of  this  kind,  of  very  high  power  and  very  low  price. 
The  immersion  lenses  of  Hartnack  may  be  divided  into  those 
with  single  and  those  with  double  correction.  In.  the  first, 
the  two  lower  lenses,  fixed  with  regard  to  each  other,  are 
shoved  up  towards  the  upper  one  (the  one  turned  towards  the 
eye-piece).  In  those  produced  more  recently,  with  apparatus 
for  double  adjustment,  the  middle  lens  also  changes  its  relative 
position  to  the  lower  lens  in  a  determined  ratio  during  the 
turning.* 

*  A  few  additional  remarks  on  the  use  of  immersion  lenses  may  here  be  in  place. 
With  a  glass  rod  or  a  camel's-hair  pencil  a  drop  of  water  is  placed  on  the  cover- 
ing glass,  and  a  second  one  on  the  under  surface  of  the  lens.  The  lens  is  then 
carefully  approached  towards  the  object  till  the  two  drops  flow  together  and 
the  focus  is  accurately  adjusted.  By  turning  the  screw,  it  will  soon  be  ascer- 
tained whether  the  image  assumes  sharper  or  less  delicate  contours,  and  thus 
the  best  adjustment  will  soon  be  found.  With  Hartnack' s  arrangement,  after 
each  correction  of  the  objective,  the  focus  is  naturally  to  be  readjusted  ;  this 


TESTING    THE    MICROSCOPE.  61 

In  indicating  the  basis  on  which  the  optical  advantage  of  such 
an  immersion  system,  in  contradistinction  to  the  ordinary  "  dry  " 
combinations,  is  founded,  we  will  permit  one  of  the  greatest 
authorities  to  speak.  Harting,  in  an  interesting  paper,  remarks 
as  follows : — 

"As  the  water  is  a  stronger  light-refracting  medium  than  air, 
the  reflection  of  the  rays  of  light  is  much  diminished  at  the 
upper  surface  of  the  cover  and  at  the  under  surface  of  the 
objective,  indeed,  it  almost  entirely  ceases.  Hence,  more  rays 
of  light  pass  into  the  microscope,  and  the  thin  stratum  of  water 
has  nearly  the  same  effect  as  an  enlargement  of  the  angle  of 
aperture.  This  favorable  modification  influences  chiefly  the 
peripheral  rays,  which  fall  most  obliquely.  The  peripheral 
rays  have  most  influence  on  the  formation  of  the  image,  which 
takes  place  in  front  of  the  eye-piece ;  and  as,  by  their  passing 
through  a  transparent  object,  they  are  for  the  most  part  de- 
flected from  their  course,  and  the  slight  deviations  thus  caused 
become  visible  in  the  image,  the  defining  power  of  the  micro- 
scope must  necessarily  be  increased  by  the  stratum  of  water." 

As  this  stratum  of  water  exerts  the  same  effect  as  an  increased 
thickness  of  the  glass  cover,  it  must  produce  an  entire  change 
in  the  spherical  and  chromatic  aberration.  We  also  notice  that 
objectives  intended  for  immersion  give  only  inelegant  and  ob- 
scure images  when  used  without  the  stratum  of  water.  The 
intercalated  stratum  of  water  is,  therefore,  an  integral  con- 
stituent, a  new  optical  element  of  the  combination,  and  may 
exert  an  advantageous  influence  in  the  removal  of  the  residuary 
secondary  aberration. 

In  a  third  manner,  finally,  the  optical  power  of  an  objective 
system  is  increased  by  the  stratum  of  water.  As  the  latter  acts 
like  a  covering  glass,  and,  as  we  have  seen  above,  the  lenses 
must  approach  each  other  in  proportion  to  the  increase  in  its 


is  not  the  case,  however,  with  those  of  the  English  opticJans,  in  which  the 
position  of  the  lowermost  lens  remains  unaltered  during  the  correction. 
The  middle  position  of  the  correcting  apparatus  of  Hartnack's  immersion 
system  corresponds  to  a  thickness  of  the  covers  of  about  0.1  mm.  After 
being  used,  the  under  surface  of  the  objective  is  to  be  carefully  dried  with  a 
fine  cloth. 


62  SECTION    FOTJKTH. 

thickness,  the  magnifying  power  and  the  angle  of  aperture  are 
thereby  also  increased. 

Harting  shows  what  may  be  obtained  by  this  means.  In 
testing  one  of  Hartnack's  objectives,  made  in  the  year  1860,  he 
obtained,  with  the  various  adjustments  of  the  apparatus  for 
correction,  an  angle  of  aperture  of  1C6  to  172°,  with  an  avail- 
able portion  of  135  to  140°,  and  a  focal -distance  of  1.8  to  1.6 
mm.  A  stronger  objective  of  Powell  and  Lealand,  of  London, 
had  an  angle  of  aperture  of  175  to  176°,  with  an  aperture  of 
145°,  and  a  focal  distance,  with  the  closest  approximation  of 
the  lenses,  of  1.36  mm.  Its  performance  was  the  same  as  Hart- 
nack's objective,  and  if  any  difference,  however  slight,  existed, 
Powell  and  Lealand's  objective  was,  according  to  Harting's  test, 
the  strongest. 

Ten  years  have  passed  since  that  time  and  meanwhile  many 
changes  have  taken  place.  Hartnack's  immersion  objectives 
Nos.  9  and  10,  with  angles  of  aperture  of  about  170  and  175°, 
and  the  nominal  focal  distances  of  -fa  and  ^  of  an  inch,  have 
obtained  the  most  universal  acceptance.  A  still  stronger  sys- 
tem, No.  11, 11g-//,  with  a  total  angle  of  aperture  of  176P,  was 
soon  afterwards  introduced  by  this  optician.  Hartnack  has  re- 
cently constructed  an  entire  series  of  very  powerful  objectives. 
No.  12  corresponds  to  ^y",  "No.  16  to  -£$",  and  the  highest,  No. 
18,  to  TV'>  of  the  English. 

It  is,  self -evidently,  of  great  practical  value  to  find  objects 
which  are  as  homogeneous  as  possible,  and  of  such  delicate  and 
fine  texture  that,  in  their  resolution,  the  optical,  or,  more  cor- 
rectly speaking,  the  penetrating  power  of  a  lens  may  be  accu- 
rately estimated.  They  are  called  "test  objects.""  Their  study 
is  of  interest  and  importance.  To  the  beginner,  who  is  desirous 
of  ascertaining  the  capacity  of  the  instrument  which,  perhaps, 
he  has  but  recently  obtained,  such  test  objects  are  to  be  recom- 
mended as  discipline;  since  their  resolution  is  by  no  means 
easy,  and  with  them  the  accurate  adjustment  of  the  focus,  and 
the  skilful  application  of  the  illumination,  may  be  learned. 
Some  of  these  test  objects,  the  finer  ones,  are  so  difficult  as  to 
occupy  the  beginner  for  hours  in  vain,  and  may  occasion  much 
labor  oven  for  the  practised.  By  careful  practice  one  may 


TESTING   THE    MICROSCOPE.  63 

arrive  at  a  certain  virtuosoship,  and  thus,  in  a  few  minutes, 
appease  the  novice,  who  possibly  begins  to  despair  of  his  instru- 
ment, by  showing  him  an  example  of  what  it  is  capable  of  per- 
forming in  skilful  hands.  Then  the  endeavor  to  discover  finer 
and  more  difficult  test  objects,  thus  always  holding  a  higher  aim 
before  the  optician,  has  led  to  the  great  emulation  existing  at 
the  present  time  in  the  construction  of  objectives.  It  is  there- 
fore unjustifiable  to  regard  the  study  of  such  tests  with  con- 
tempt, as  is  occasionally  to  be  observed  among  notable  micro- 
scopists.* 

In  the  course  of  time,  such  test  objects  have  been  frequently 
highly  commended  and,  with  the  increasing  perfection  of  prac- 
tical optics,  again  abandoned.  Therefore,  all  those  which  were 
recommended  before  1840,  all  the  various  hairs  and  scales  of 
butterflies  and  wingless  insects,f  may  be  regarded  as  conquered 
territory.  To  attempt  to  test  a  first-class  modern  microscope 
with  these  expedients  of  a  former  epoch,  would  be  an  insult  to 
the  optician  from  whose  establishment  the  instrument  has  pro- 
ceeded. 

In  the  year  1846,  II.  von  Mohl,  one  of  the 
first  judges  of  the  microscope,  called  attention 
to  the  brighter  scales  of  the  anterior  wing 
of  the  Papilio  Janira  $  ,  a  knowledge  of  which 
he  had  obtained  through  the  Italian,  Amici, 
the  most  renowned  constructor  of  micro- 
scopes of  that  epoch.  Together  with  the 
familiar  longitudinal  lines,  fine,  closely  ap- 
proximated (T^VO"  mm-  apart),  sharp,  and  not 
granular  transverse  lines  appear,  fig.  50. 
Mohl  remarked,  at  that  time,  that  with  a  Fig.so.  scaieofpapuio 

7  Janira. 

magnifying  power  not  exceeding  200,  noth- 

*  M.  Schiff  has  expressed  the  same  sentiments  with  regard  to  the  value  of 
test  objects.  We  cannot  agree,  however,  with  many  of  his  views  regarding 
the  diatoma  scales. 

f  It  is  well  known  that  the  trichina  disease  has,  in  our  day,  led  to  the  pro- 
duction of  an  innumerable  quantity  of  cheap  instruments,  intended  only  for 
the  microscopic  examination  of  meat.  The  well-known  scales  of  the  Lepisma 
Saccharinum,  a  wingless  insect,  are  useful  for  testing  them.  We  shall  refer 
to  this  subject  at  the  examination  of  the  muscles. 


64  SECTION   FOURTH. 

ing  was  to  be  seen  of  these  transverse  lines,  and  that  it  was 
necessary  to  have  an  instrument  with  very  strong  and  very  good 
lenses  to  recognize  the  transverse  markings,  sharply  and  dis- 
tinctly, with  220  to  300  fold  linear  enlargement.  He  cited  only 
the  microscopes  of  Amici,  Plossl,  and  a  single  one  of  Ober- 
hauser,  as  at  that  time  standing  the  test  thoroughly.  I  still  re- 
member very  well  how  I,  as  a  student,  with  a,  for  that  time, 
very  serviceable  Shiek's  microscope, — my  companion  for  many 
years, — was  obliged  to  vex  and  trouble  myself  to  obtain  only  a 
passable  view  of  these  transverse  markings. 

Nowadays  an  instrument  would  be  called  bad  which,  with 
a  magnifying  power  of  200,  left  anything  to  be  desired  in  re- 
solving a  Janira  scale.  By  means  of  a  large  Plartnack  instru- 
ment, made  in  the  year  1861, 1  see  them  (in  a  test  object  coming 
from  Kellner)  without  any  precautionary  measures,  even  with 
120-fold  enlargement  (objective  No.  5,  eye-piece  No.  2).  At 
the  present  time,  the  scales  of  the  Papilio  Janira  deserve  to  be 
regarded  as  a  means  of  testing  objectives  of  medium  strength 
only. 

The  silicious  envelopes  of  the  Diatomacese  have  taken  the 
place  of  the  butterfly  scales ;  those  with  the  finest  and  most 
closely  placed  markings  are  employed. 

The  fineness  of  the  markings  may  be  represented  in  a  table 
collated  by  Harting  from  English  sources. 

The  Pinnularia  nobilis          has  from    4  to    6  striations  in  the  7^7  of  a  millim. 

"     Pleurosigmaformosnm    "  u     12  to  14  "  "  "  " 

"            "            attenuatum"  "    15  to  16  "  "  "  " 

"            "            angulatum   "  "    22  to  23  "  u  "  " 

"    Grammatophora  marina  "            25  "  "  "  " 

"    Nitzschia  sigmoidea        "  "    30  to  31  "  "  "  " 
"    Navicula  rhomboides 

(affinis,  Amicii)             "             30  "  "  "  " 
u     Surirella  gemma  (Ion- 
git  adinal  lines)             "  "    30  to  32  "  "  "  " 
"    Grammatophora  subti- 

lissima                           "  "    32  to  34  "  "  "  " 

"    Frustulia  saxonica           "  "    34  to  35  "  "  "  " 

Of  the  numerous  Diatomacese  there  are  several  which  deserve 
mention  as  being  of  particular  importance  ;  namely, — the  Pleu- 


TESTING    THE    MICROSCOPE. 


65 


rosigma  angulatum  and  Nitzschia  sigmoidea,  already  mentioned 
in  the  table  ;  then,  the  Navicula  Amicii,  Surirella  Gemma,  and 
the  Grammatophora  subtilissima,  made  known  by  the  deceased 
Professor  Bailey,  of  North  America.  The  last  two  objects  (we 
have  these  always  in  mind  as  they  are  to  be  obtained  from 
Bourgoyne  of  Paris)  are  extremely  difficult,  and  in  resolving 
them  the  microscope  withstands  a  hard  trial.  Reinicke  (Bei- 
trage  zur  neueren  Mikroskopie,  3.  Heft.  Dresden,  1863)  has 
called  attention  to  the  Frustulia  saxonica, 
mounted  in  Canada  balsam,  as  a  very  subtile 
test  object.  Its  transverse  lines  do  not  stand 
very  close  to  each  other,  but  are  very  delicate 
and  difficult  to  perceive.  At  the  last  London 
Industrial  Exhibition  the  Navicula  affinis, 
mounted  in  Canada  balsam,  was  used  as  a 
test  object.  Their  longitudinal  striations  are 
resolved  without  difficulty,  while,  on  the  con- 
trary, their  transverse  lines  are  very  sharp 
and  fine,  so  that  I  must  pronounce  their  solu- 
tion (in  Bourgoyne's  preparations)  more  diffi- 
cult than  the  Surirella  Gemma  and  Gramma- 
tophora. Bailey  has  also  recommended  the 
Hyaloidiscus  subtilis."*  . 

The  Pleurosigma  angulatum,  fig.  51,  fur- 
nishes, with  oblique  light,  an  excellent  means 
of  testing  the  resolving  power  of  good  objec- 
tives of  medium  and  greater  power,  but  should  expose  all  its 


Fig.  51.     Pleurosigma 
angulatum. 


*  J.  D.  Holier,  of  Wedel,  Holstein,  has  recently  produced  a  very  excellent 
but  expensive  Diatom  test-plate.  Each,  one  contains  20  Diatoms,  arranged 
according  to  their  value  as  test  objects,  as  designated  by  Dr.  Grunow,  namely : 
1.  Triceratium  Favus ;  2.  Pinnularia  nobilis ;  3.  Navicula  Lyra  var.  ;  4.  N. 
Lyra  ;  5.  Pinnularia  interrupta  var. ;  6.  Stauroneis  Phcenicenteron  ;  7.  Gram- 
matophora marina  (more  coarsely  marked  than  Bourgoyne's  variety) ;  8.  Pleuro- 
sigma Balticum  ;  9.  P.  acuminatum;  10.  Nitzschia  amphioxys  ;  11.  Pleurosigma 
angulatum  ;  12.  Grammatophora  Oceanica  subtilissima  (marina) ;  13.  Surirella 
Gemma  (transverse  lines) ;  14.  Nitzschia  sigmoidea  ;  15.  Pleurosigma  Fasciola 
var.  ;  16.  Surirella  Gemma  (longitudinal  lines) ;  17.  Cymatopleura  elliptica ; 
18.  Navicula  crassinervis,  Frustulia  Saxonica ;  19.  Nitzschia  curvula ;  20. 
Amphipleura  pellucida.  Eodig,  of  Hamburg,  also  issues  a  similar  Diatom 
plate. 

5 


66  SECTION    FOURTH. 

delicate  markings  with  a  good  immersion  lens  with  simple  cen- 
tral illumination.  With  oblique  light  this  test  object  is  entire- 
ly too  easy  for  immersion  lenses. 

If  the  examination  of  the  Pleurosigma  angulatum  is  com- 
menced with  a  weak  objective,  it  appears  smooth  and  without 
markings.  Passing,  together  with  the  application  of  oblique 
illumination,  to  stronger  lenses,  a  period  arrives  when  systems 
of  lines  sparkle  forth,  which  run,  in  part,  diagonally  over  the 
scale,  in  part  obliquely  and  crossing  each  other.  Sometimes 
the  one,  sometimes  the  others  of  these  lines  are  most  distinct, 
according  as  the  oblique  light  passes  through  the  scale. 

They  come  forth  gradually  and  quite  sharp,  and  in  fortunate 
cases  one  may  distinguish  all  three — the  two  oblique  ones  cut- 
ting each  other  at  angles  of  nearly  60°  (not  53) — at  the  same 
time  with  perfect  distinctness,  all  lying,  according  to  my  view, 
in  the  same  plane.  It  is  still  believed  that  we  have  here  to  do 
with  perfectly  straight  lines. 

By  using  an  immersion  lens  with  central  illumination,  they 


Fig.  52.    Areolations  of  the  Pleuro-          Fig.  53.    Areolations  of  the  Pleurosigma  angulatum. 
sigma  angulatum ;  from  a  photograph. 

appear  to  surround  a  series  of  extremely  small  and  very  delicate 
hexagonal  areolations  in  close  approximation,  fig.  52.  These 
appear,  according  as  the  focus  is  altered,  either  dark  and  sur- 
rounded by  bright  margins,  fig.  53,  or  bright,  with  dark  mar- 
gins, fig.  52.  So  much  may  be  stated  with  entire  certainty. 
Now  arises,  however,  the  difficult  and  by  no  means  definitely 
settled  question : — Are  the  areolations  concave  and  their  mar- 


TESTING   TIIE    MICROSCOPE.  67 

gins  elevated,  or,  on  the  contrary,  are  the  latter  furrows  between 
projecting  areoe  ?  Both  propositions  have  been  sustained  by 
distinguished  observers.  I  formerly  regarded  the  depression  as 
probable,  and  also  that  the  focus  was  correctly  adjusted  when 
the  areolations  appear  dark.  M.  Schultze  has  also  expressed  the 
same  opinion,  in  accordance  with  certain  rules  (see  below)  estab- 
lished by  AVelcker.  I  afterwards  adopted  the  contrary  view. 
This  does  not  appear  to  be  the  place  to  enter  further  into  this 
subject. 

A  good  objective,  magnifying  about  80  or  100  times,  should, 
with  the  proper  oblique  illumination,  enable  one  to  recognize 
the  systems  of  lines  sharply  and  distinctly  on  all  the  scales; 
while  weaker  objectives,  magnifying  40  or  50  times,  should 
show  something  of  the  lines.  "When  it  is  found  impossible  to 
obtain  oblique  illumination,  this  inconvenience  may  be  remedied 
by  means  of  a  condenser,  with  its  central  portion  obscured. 
Oblique  illumination  and  a  stage  capable  of  rotation  are  of  great 
assistance.  Hartnack's  immersion  lenses  Nos.  9,  10,  or  .11  show 
the  arose  very  distinctly  and  beautifully,  with  central  illumina- 
tion, and  even  with  an  unfavorable  sky.  Other  opticians, 
Amici,  Kachet,  and  some  English  and  German  artists,  have  also 
been  able  to  resolve  them  with  their  strongest  lenses  in  the 
manner  last  mentioned.  Hartnack's  newly  constructed  objec- 
tive No.  9,  not  intended  for  immersion,  accomplishes  the  same, 
as  I  have  myself  witnessed,  likewise  his  latest  No.  8 ;  even 
an  excellent  No.  7,  received  several  years  ago,  gives  the  same 
result,  with  similar  central  illumination  and  elevated  concave 
mirror. 

The  other  test  objects  already  mentioned,  Nitzschia  sigmoidea, 
Surirella  Gemma,  Grammatophora  subtilissima,  and  Navicula 
rhomboides  are  much  more  difficult,  and  can  only  be  resolved  by 
means  of  suitable  oblique  illumination  and  very  accurate  correc- 
tion of  the  objective.  The  first  is  the  easiest;  the  last  three,  on 
the  contrary,  serve  to  test  the  best  and  most  powerful  modern 
immci-sion  lenses. 

As  was  just  mentioned,  the  Nitzschia  sigmoidea  is  the  easiest 
of  these  objects  to  resolve.  With  oblique  illumination,  the  long 
and  narrow  valve  shows  a  series  of  very  fine  and  compact  trans- 


68 


SECTION    FOURTH. 


verse  lines.    Bourgoyne's  preparations  of  the  Nitzschia  sigmoidea 

are  mounted  dry. 

The  Surirella  Gemma,  fig.  54,  is  a  very  delicate  test  object, 
and  only  to  be  mastered  with  much  pains.  Seen 
from  its  broad  surface,  the  oval  disk  shows  paral- 
lel ridges  running  as  far  as  the  central  line.  Be- 
tween these  appear  very  readily  a  series  of  fine, 
but  distinct,  transverse  lines.  It  is  these  latter 
lines,  cutting  the  transverse  ones  at  right  angles, 
which  give  the  Surirella  Gemma  its  value  as  a  test 
object  of  the  first  class.  Undulating  curved  lines 
of  extreme  fineness  should  appear,  which  give  to 
the  whole  an  interwoven  appearance  like  basket- 
work  (fig.  55).  "With  the  aid  of  his  best  lenses, 
JZartnack  even  succeeded  in  resolving  these  undu- 
lating lines  into  a  series  of  very  narrow  hexagonal 
pig.  54.  surireiia  areolations  (fig.  56).  Bourgoyne's  preparation  is 

Gemma'  also  mounted  dry. 


Fig.  65.  Longitudinal  Tines  on 
the  silicious  envelope  of  the  Suri- 
rella Gemma. 


Fig.  56.  The  same, 
resolved  into  areola- 
tions. 


The  Grammatophora  subtilissima,  mounted  by  Bourgoyne  in 
Canada  balsam,  is  equally  difficult.  I  do  not  know  whether  it 
is  identical  with  the  species  first  used  by  the  American  micro- 
scopist,  Professor  Bailey,  of  West  Point,  U.  S.  Besides,  it 
seems  that  two  kinds  of  valves  of  unequal  difficulty  have  there 
been  pronounced  to  be  Grammatophora  subtilissima. 

Seen  from  its  broad  surface,  the  silicious  envelope  presents 
the  appearance  of  an  oblong  square,  with  blunted  corners  (fig. 
57,  1).  It  is  divided  into  three  regions  by  the  two  peculiarly 
curved  longitudinal  furrows.  The  two  lateral  regions  (a)  of 
every  valve  should  exhibit  very  fine  and  compact  transA^erse 
lines  (20),  with  the  aid  of  good  oblique  illumination.  The  cen- 
tral portion  does  not  show  any  markings. 


TESTING    THE    MICROSCOPE. 


69 


Fig.  57.    1  Grammatophora  sub- 
tilissima.    2  Transverse  lines  of  the 


This  is,  however,  only  a  portion  of  the  markings  we  are  at 
present  able  to  recognize.      Other  sharper  and  more  coarsely 
marked  species  of  the  genus  Gramma- 
tophora show  these  transverse  lines,  / 
intermingled  with  a  double  series  of 
oblique  lines  crossing  each  other  at 
an  angle  of  60°,  so  that  exactly  the 
same  markings  result  which  we  have 
previously  described  in  the  Pleuro- 
sigma  angulatum.   These  oblique  lines 
of  the  Grammatophora  subtilissima 
also   appear  to  be    quite   separated. 
Hartnack  informs  me  that  he  has  suc- 
ceeded in  resolving  them  with  one  of  his  strongest  objectives, 
and  I  believe  that  I  have  myself  caught  at  least  a  glimpse  of 
them,  with  an  immersion  lens  ISTo.  10. 

We  add,  finally,  a  few  remarks  on  the  Navicula  rhomboides, 
sporangial  form*  (fig.  58).  Its  somewhat 
undulating,  longitudinal  lines  (a)  may  be 
recognized  with  oblique  light  and  a  good 
immersion  lens,  without  much  trouble.  They 
may  be  from  0.0002  to  0.00018  of  a  Paris 
line  distant  from  each  other.  The  elegant 
transverse  lines  (b)  of  the  specimen  in  Canada 
balsam  appear  much  more  compact  and  ex 
Fig.  58.  Navicuia  rhom-  tremelv  delicate.  To  recognize  them,  very 

boides.    a    longitudinal,  6  •/  J 

transverse  lines.  oblique  light  and  the  most  accurate  correction 

of  the  immersion  objective  is  necessary. f 

All  organic  test  objects  have,  as  a  fault,  the  peculiarity  that 
they  are  not  exactly  alike^but  are,  in  the  most  fortunate  cases, 
only  very  similar.  It  was,  therefore,  a  fortunate  idea  of  No- 

*  The  Navicula  in  question  was  used  at  the  last  London  Industrial  Exhibi- 
tion, as  N.  affinis,  and  was  given  to  me  in  the  form  of  a  preparation  by  Bour- 
goyne,  as  N.  Amicii.  I  have*to  thank  Th.  Eulenstein  for  the  definition  given 
in  the  text. 

f  The  recognition  of  these  transverse  lines  may  be  accomplished  almost 
instantly  by  an  expert,  with  a  Hartnack  No.  11  immersion  objective.  I  have 
succeeded  in  doing  this,  though  with  some  trouble,  even  with  a  No.  9  of  this 
optician.  Let  me  remark,  incidentally,  that  the  latter  combination  should 
also  resolve  the  Surirella  Gemma  and  Grammatophora  subtilissima. 


70  SECTION   FOTJKTH. 

bert's  to  produce  glass  plates  with,  bands  of  parallel  lines,  the 
distances  between  the  lines  constantly  decreasing.  The  oldest 
of  these  plates,  made  about  1845,  presented  ten  bands.  In 
the  first  band,  the  distance  between  the  lines  was  -j-oVir"',  m 
the  last,  ^nnnr'"'  At  tne  present  time,  with  the  progress  of 
practical  optics,  such  plates  would  no  longer  afford  a  means  of 
testing  first-class  microscopes.  Robert  afterwards  made  plates 
with  30  bands ;  but  these  marvellous  productions  of  art  cost  30 
thalers.  Quite  recently  he  has  issued  a  plate  with  19  bands; 
the  lines  in  its  last  division  are  10ooo  of  a  line  apart.  Thus 
markings  as  fine  as  those  of  the  Diatomacese  have  been  made 
by  art.  Nevertheless,  these  wonderful  plates  of  Robert's  also 
have  the  fault  of  not  being  identical,  although,  in  the  most 
recent  ones,  the  differences  are  almost  imperceptible.  Diversity 
of  opinion  still  prevails  regarding  the  resolution  of  the  last 
bands,  and  this  is  connected  with  the  still  unsettled  question,  as 
to  where  the  limits  of  accurate  vision  with  our  modern  micro- 
scopes lies.  "We  here  introduce  a  table  of  the  divisions  of  the 
last  two  test  plates : — 

Plate  with  30  bands.  Plate  with  19  bands. 

1.     Band  0.001000  of  a  Paris  line.  1.  Band  T^lf  of  a  Paris  line. 

5.         "     0.000550             "  2.  " 

10.         "     0.000273             «  3.  " 

15.         "    0.000200            "  4.  « 

20.         «    0.000167            "  5.  « 

25.         "     0.000143             "  6.  " 

30.        «    0.000125            "  7.  " 

8.  «     ^nr 

9-  60  oO 

10.'  «  rfn 
11-  "  WJFIT 
«•  "  «Vrr 

13-  "      T^TT 

I*-  "      Ww 

15-  "  ^Ar 

16.  "  ^ww 

17.  "  ^T 

18.  «  TT^HT 

*"•  10000 


TESTING    THE    MICROSCOPE.  71 

The  resolution  of  these  lines  with  oblique  light  has  been 
employed  as  a  means  of  testing  objectives.  Harting  was  able, 
years  ago,  with  a  Hartnack's  immersion  lens  No.  10,  to  recognize 
the  lines  in  the  30th  band  of  the  older  plates,  and  the  resolution 
of  the  25th,  26th,  and  even  the  27th  band  is  not  an  unusually 
great  achievement.  M.  Schultze  succeeded  in  resolving  the  15th 
band  of  the  more  recent  plate,  and  I  afterwards  resolved  the 
17th  band  with  objective  No.  11.  In  the  year  1869,  an  Ameri- 
can, Woodward,  whom  we  have  to  thank  for  excellent  photo- 
graphs of  test  objects,  also  mastered  the  19th  band  of  this  won- 
derful test  plate. 

Several  years  since,  Schultze  tested  a  series  of  the  best  mod- 
ern objectives  with  central  illumination.  The  highest  perform- 
ance consisted,  at  that  time,  in  resolving  the  9th  band  with  an 
immersion  lens  No.  10  of  Ilartnack,  and  one  of  Merz's  -fa".  I 
have  repeated  this  experiment.  My  immersion  objective  No. 
11  resolved  the  12th,  less  distinctly  the  13th,  No.  10  the  llth, 
and  the  combination  No.  7  of  most  recent  construction,  the  7th 
band  of  this  test  plate. 

We  have,  finally,  to  discuss  the  question  as  to  what  precepts 
and  advice  are  to  be  given  to  those  who  desire  to  procure  a 
microscope;  how  should  the  instrument  be  constructed,  and 
which  optical  establishment  deserves,  at  present,  to  be  most 
recommended. 

lie  who  desires  to  possess  a  first-class  instrument  will  gener- 
ally select  one  of  the  large  microscopes  with  a  horse-shoe  stand, 
fig.  59,  as  constructed  by  Oberhauser  and  imitated  by  other 
opticians.  Its  convenience  of  manipulation,  combined  with  a 
certain  simplicity,  render  it  a  truly  model  stand.  The  large 
stage,  its  capability  of  being  rotated  (which,  however,  requires 
very  accurate  workmanship,  and  is  therefore  expensive),  the 
micrometer-screw  for  the  fine  adjustment,  and  the  mobility  of 
the  mirror,  are  extraordinary  advantages.  The  illuminating 
apparatus  might,  it  is  true,  be  improved,  still  it  suffices  for 
most  purposes.  When  the  stands  which  the  English  opticians 
select  for  their  larger  instruments  (see  page  31,  fig.  32)  are 
compared  with  it,  they  appear  to  be  unpleasantly  loaded  with 
screws  and  unessential  appurtenances,  which  inconvenience  one 


72 


SECTION    FOUKTH. 


who  daily  works  with  the  instrument,  as  it  is  better  to  do  with 
the  human  hand  much  which  is  there  allotted  to  mechanical 
contrivances. 


Fig.  59.    Hartnack's  large  horse-shoe  microscope. 

For  medical  purposes  the  rotary  stage  may  be  readily  dis- 
pensed with;  less  readily  the  oblique  illumination;  and  this, 
which  may  be  added  with  little  expense,  should,  indeed,  no 
longer  be  omitted  from  any  instrument  of  medium  class. 
Smaller  horse-shoe  stands,  similar  in  construction  to  the  larger 
stand,  but  without  the  rotary  stage,  deserve,  therefore,  to  be 


TESTING    THE    MICROSCOPE.  73 

especially  recommended.  Still  smaller  stands  should  possess  a 
plane  and  concave  mirror,  and  at  least  a  rotary  diaphragm  to 
regulate  the  illumination,  or,  which  is  better,  several  cylindrical 
diaphragms,  as  well  as  a  stage  an  inch  and  a  half  wide.  When 
there  is  no  oblique  illumination,  a  simple  condenser,  similar  to 
the  one  represented  in  fig.  24,  may  be  used  as  a  substitute. 
When  there  is  but  a  simple  mirror,  no  rotary  diaphragm,  and 
the  stage  is  very  narrow,  as  is  the  case  in  Hartnack's  older 
microscope  a  1'hospice,  the  stand  is  certainly  deficient. 

Nevertheless,  the  mechanical  portion  of  a  microscope  is  a 
secondary  consideration  and  of  minor  importance ;  in  the  opti- 
cal apparatus  is  founded  the  actual  value  of  the  instrument. 

One  or  the  other  form  of  instrument  will  be  selected,  accord- 
ing as  a  greater  or  lesser  price  can  be  afforded.  Beginners, 
especially,  should  not  have  recourse  to  the  largest,  most  expen- 
sive microscopes,  as  their  manipulation  is  more  difficult,  and 
considerable  practice  is  required  before  very  powerful  first-class 
lenses  can  be  used. 

The  strangest  notions  not  unf  re'queiitly  prevail  with  regard  to 
the  optical  portion.  How  often  is  the  question  still  heard  :  How 
much  does  this  instrument  magnify  ?  How  often  are  micro- 
scopes ordered  from  an  optician,  with  a  magnifying  power  of 
from  5-600  diameters.  Nothing  shows  a  greater  misconception 
of  the  optical  performance  of  our  instrument,  as  it  is  only  neces- 
sary to  add  a  perhaps  uselessly  strong  eye-piece,  to  change  a 
serviceable  magnifying  power  of  400  diameters  into  a  com- 
pletely unserviceable  one  of  800,  and,  therefore,  of  no  value  to 
the  instrument. 

The  individual  objectives  with  the  various  eye-pieces  form, 
each  for  themselves,  a  particular  microscope.  For  this  reason, 
one  should  have  at  least  a  twofold  combination  of  lenses,  if  pos- 
sible, three, — a  weak,  a  medium,  and  a  strong  one.  A  double 
combination  of  lenses  may  be  obtained  from  one  system,  in  the 
most  economical  manner,  by  removing  its  lowermost  lens. 
Many  of  the  most  simply  constructed  instruments  have  only 
one  such  objective,  with  two  eye-pieces.  Good  microscopes  of 
this  kind  may  be  obtained  for  20  thalers.  It  is  better  to  have 
several  objectives  with  inseparable  lenses. 


74  SECTION    FOURTH. 

"We  would  here  call  to  mind  what  we  have  previously  said 
with  regard  to  the  great  value  of  weaker  powers.  They  should 
never  be  wanting.  At  least  one  objective  of  medium  strength 
is  also  a  valuable  addition.  Finally,  a  stronger  objective,  which, 
with  a  weak  eye-piece,  magnifies  from  200  to  250  times,  and, 
with  a  stronger  one,  affords  a  good  and  thoroughly  serviceable 
magnifying  power  of  300  to  350,  should  not  be  wanting  on  any 
microscope. 

These,  usually,  completely  suffice,  especially  if  another  eye- 
piece with  a  glass  micrometer  is  added.  Such  instruments  are 
to  be  purchased  for  30,  40,  and  50  thalers,  according  to  the  stand, 
and,  when  obtained  from  the  best  modern  establishments,  stand 
higher,  as  to  their  capabilities,  than  the  large  microscopes  con- 
structed fifteen  years  ago  at  three  or  four  times  their  price. 

Stronger  objectives  are  very  seldom  required ;  their  addi- 
tion naturally  increases  the  cost  considerably.  For  the  com- 
^  f  mencement  we  would  advise  the  omis- 

S*on  °^  ^e  very  strongest  objectives, 
especially  those  with  apparatus  for  cor- 
rection  which  are  delicate  to  manipu- 
late,  as  well  as  immersion  lenses  (fig. 
60),  and  to  select  in  their  place  a  coin- 
Fig.  GO.  Hartnack's  immersion  ob-  bination  which  works  drv.  "With  this, 

jective  No.  10.  J      .  .     ' 

the  magnifying  power  might  be  in- 
creased to  450  or  600,  and  rarely,  even  in  extended  scientific 
researches,  would  a  higher  magnifying  power  be  missed.  Such 
instruments,  of  excellent  quality,  may  be  bought  on  the  conti- 
nent for  about  70  or  80  thalers. 

Other  more  or  less  expensive  accessories,  such  as  drawing 
and  polarizing  apparatuses,  are,  as  a  rule,  added  to  the  larger 
instruments  only. 

The  value  of  a  microscope  being  founded  on  its  optical  por- 
tion, on  the  excellence  of  its  lenses,  the  question  here  arises  as  to 
the  present  productions  of  the  various  optical  establishments. 
It  is  very  difficult  to  render  an  impartial  decision  on  this  point. 
Disregarding  a  certain  amount  of  odium  in  which  one  would  be 
placed  with  the  opticians  not  accorded  the  first  rank,  one  should 
have  just  made  a  long  journey,  instituted  for  this  purpose, 


TESTING   THE    MICROSCOPE.  75 

through  Germany,  France,  England,  and  North  America,  for  in 
this  department  our  industrial  epoch  exhibits  a  steady  progress, 
one  maker  being  surpassed  by  another. 

The  problem  of  the  construction  of  weak,  medium,  and  ordi- 
nary stronger  objectives  has  been  solved  in  a  perfectly  satisfac- 
tory manner  by  a  considerable  number  of  modern  opticians,  so 
that  every  year  a  large  number  of  excellent  microscopes,  thor- 
oughly adequate  to  all  the  requirements  of  the  physician,  are 
put  in  the  market.  It  is  true  that  certain  objectives  of  one 
maker  are  superior  to  the  same  lenses  of  another  maker ;  but 
these  differences  do  not  appear  to  exert  any  great  influence  on 
their  practical  requirements,  and  are  only  to  be  discovered  by 
the  practised  eye.  The  effort  to  obtain  a  large  angle  of  aperture 
has  stamped  modern  objectives  with  a  peculiar  character.  "VVe 
would  give  the  practical  advice,  not  to  purchase  an  instrument 
of  an  unknown  optician,  or,  at  least,  not  without  having  it  tested 
by  an  expert,  and  to  have  the  greatest  mistrust  of  all  charlatani- 
cal  recommendations,  whether  they  come  from  the  optician  him- 
self or  from  a  writer  glorifying  him. 

The  various  optical  establishments  differ  greatly  in  the  con- 
struction of  very  powerful,  or  the  most  powerful  combinations, 
as  to  the  greatest  excellence  which  may  be  accomplished  in  this 
department.  Therefore,  he  who  would  procure  a  first-class  in- 
strument should  proceed  with  circumspection. 

AVithin  twenty  years  several  large  firms  in  England  main- 
tained a  higher  rank  in  this  department  than  the  Continental 
opticians  had  obtained,  if  we  disregard  the  Italian  savant  and 
distinguished  microscope-maker,  Amici  (f  1863).  No  impartial 
person,  who  knows  how  to  test  a  microscope,  could  deny  this, 
if  he  were  to  compare  first-class  instruments  originating  in  that 
epoch.  Since  that  time  the  emulation  of  the  Continental  opti- 
cians has  spurred  the  most  skilful  on  to  even  higher  productions ; 
the  difference  has  become  less  and  less,  and  has  finally  disap- 
peared. Indeed,  a  few  which  have  been  produced  among  us  of 
late  deserve,  perhaps,  to  be  placed  higher.  At  the  same  time 
there  is  a  very  considerable  difference  in  price  between  the 
larger  kind  of  English  instruments  and  those  of  Germany  and 
France.  For  example,  a  single  objective  with  a  nominal  focus 


76  SECTION   FOURTH. 

of  y1^-  inch,  made  by  Powell  and  Lealand,  of  London,  costs  some- 
what more  than  16  pounds,  while  Hartnack,  of  Paris,  furnishes 
a  combination  equally  strong,  No.  10  a  immersion,  for  200,  and 
a  still  stronger  one,  No.  11,  for  250  francs.  The  strongest  ob- 
jective, ^y  inch,  of  the  London  firm  mentioned  is  charged  at  31 
pounds  10  shillings  in  the  price-list ;  in  that  of  the  Parisian  op- 
tician, at  500  francs. 

Large  modern  microscopes  of  the  most  renowned  English 
makers  have  not  been  accessible  to  me.  I  am,  therefore,  unable 
to  say  how  far  the  achievements  of  former  years  have  been  sur- 
passed. Several  years  ago,  Ilarting,  one  of  the  first  and  most 
profound  judges  of  the  microscope,  passed  the  highest  encomi- 
ums on  the  powerful  and  most  powerful  objectives  of  Andrew 
Ross,  as  well  as  of  Powell  and  Lealand.  Several  years  ago,  the 
^-g-  inch  objectives  of  the  latter  firm  became  quite  numerous  in 
England,  and  obtained  great  appreciation  at  the  Industrial  Ex- 
hibition in  1862.  Another  of  -^  inch  is  announced  in  the  new 
price-current.  Beale  has  praised  it  very  highly.  I  became 
acquainted  with  it  in  the  year  1866;  so  slightly,  however,  that  I 
am  unable  to  express  an  opinion. 

Among  the  Continental  opticians,  Hartnack,  of  Paris,  the 
successor  to  Oberhauser  (Place  Dauphine  No.  21),  stands  first, 
according  to  my  views.  Not  only  that  his  immersion  lenses 
have  not  as  yet  been  equalled  by  any  Continental  microscope- 
maker,  but  the  weaker  objectives,  which  are  so  very  important, 
have  also  been  very  much  improved,  and  from  the  industry  and 
carefulness  of  this  highly  accomplished  artist,  further  improve- 
ments are  to  be  expected.  Thus,  objective  No.  5  has  already  an 
angle  of  aperture  of  about  80°.  Ilartnack's  Nos.  7  and  8,  espe- 
cially, are  excellent,  and,  like  all  of  his  apparatuses,  to  be  re- 
commended for  their  slight  expense.  The  former  has  within 
a  few  years  been  brought  to  an  ever  higher  stage  of  consumma- 
tion, as  well  in  penetrating  as  in  defining  power,  as  I  know 
from  numerous  comparisons  and  tests,  and  with  an  angle  of 
aperture  of  about  100°,  forms  a  wonderful  combination  for 
histological  investigations.  No.  8  has  125-130°,  No.  9  (dry), 
155-160°  total  aperture. 

The  smallest  microscope  a  1'hospice,  with  objective  No.  7 


TESTIKO    THE    MICROSCOPE.  77 

and  a  sufficiently  broad  stage,  may  be  obtained  for  the  low  price 
of  65  francs ;  though  deficient  with  regard  to  the  illuminating 
apparatus,  it  is  nevertheless  very  serviceable  for  medical  pur- 
poses. 

A  somewhat  larger  instrument  with  a  rotary  diaphragm  and 
a  wide  stage,  with  a  weak  objective  and  the  No.  7  just  mentioned, 
together  with  several  eye-pieces,  costs  115  francs,  which  is  in- 
creased, when  the  objective  No.  8  is  added,  to  165  francs.  Dis- 
regarding the  absence  of  oblique  illumination,  we  should  scarce- 
ly wish  for  anything  further.  It  is  very  convenient  for  travel- 
ling, on  account  of  its  small  size. 

The  small  horse-shoe  microscope,  No.  viii.,  is  a  very  conve- 
nient stand,  permitting  of  oblique  illumination.  With  three 
objectives,  4,  7,  and  8,  together  with  the  necessary  eye-pieces,  it 
costs  275  francs.  During  a  series  of  years  a  considerable  num- 
ber of  instruments  of  this  kind  have  passed  through  my  hands, 
and  I  know  of  no  other  modern  microscope  which  I  should  be 
more  inclined  to  recommend  to  physicians  and  students  who  are 
able  to  afford  the  moderate  price.  If,  instead  of  a  No.  8,  an 
immersion  lens  No.  9  is  taken,  the  price  is  increased  to  390 
francs.  Besides  this  stand,  Hartnack  has  recently  introduced  a 
still  more  simplified  form,  with  a  rotary  diaphragm  and  a  bronzed 
foot.  With  objectives  4  and  7,  and  two  eye-pieces,  it  costs  140 
francs.  If  the  foot  is  replaced  by  a  simple  slab,  the  price  is  re- 
duced to  120  francs. 

Hartnack  makes  his  large  microscope  only  in  the  larger 
form,  and  with  a  rotary  stage ;  together  with  four  ordinary 
objectives  it  usually  receives  a  No.  9  immersion  lens,  costing, 
with  this  addition,  750  francs,  at  present  the  best  Continental 
instrument. 

Nachet,  of  Paris  (Nachet  et  fils,  Eue  St.  Severin  No.  17),  has 
also  obtained  a  considerable  reputation  as  a  microscope  con- 
structor. Several  large  microscopes,  constructed  several  years 
ago,  resembling  the  English  pattern,  capable  of  being  inclined, 
and  furnished  with  a  condenser,  were  very  good  for  that  time. 
What  progress  Nachet  has  since  made  in  the  construction  of 
the  most  powerful  objectives,  I  have  unfortunately  not  become 
sufficiently  informed.  I  had  recently  in  my  hands  an  immer- 


78  SECTION    FOURTH. 

sion  objective  No.  7,  a  little  weaker  than  Ilartnack's  No.  10 ; 
it  was  very  good.  Several  small  microscopes  which  I  formerly 
tested  wTere,  as  well  in  their  mechanical  as  in  their  optical 
portions,  excellent  and  very  cheap,  costing  only  200  francs. 
Nachet's  prices  are  as  follows : — The  large  stand,  fig.  33, 
fashioned  after  the  English  microscopes,  and  arranged  for 
inclining,  with  very  numerous  accessories  and  seven  objectives, 
costs  1,300  francs ;  the  older  large  instrument  1,150,  and 
more  simply  furnished  G50  francs.  Smaller  instruments,  with 
various,  in  part  very  convenient  stands,  may  be  obtained  from 
Nachet  for  500,  380,  200,  150,  125  and  70  francs. 

The  older  firm  of  Chevalier  has  recently  taken  a  new 
start,  through  the  son,  Arthur  Chevalier  (Palais  Royal,  No. 
158).  A  competent  judge,  von  Ileurck,  has  recently  given 
prominence  to  Chevalier's  optical  productions.  Unfortunately, 
I  have  not  as  yet  seen  anything  from  this  establishment. 

Among  the  opticians  residing  in  Germany  (who  have  de- 
veloped the  most  commendable  and  successful  emulation),  we 
will  first  mention  a  firm  of  Munich,  G.  &  S.  Merz,  into  whose 
hands  has  passed  the  renowned  establishment  of  Fraunhofer 
and  Utzschneider.  We  would  especially  commend  one  of  their 
smaller  instruments.  It  is  a  horse-shoe  stand,  and  is  provided 
with  three  eye-pieces  and  two  objectives,  with  the  nominal  foci 
of  ^  and  -£%".  The  latter  objective  is  of  excellent  construction 
and  magnifies  from  240  to  480  and  720  diameters.  This  micro- 
scope may  be  bought  for  77  guldens ;  it  is  one  of  the  most 
praiseworthy  of  which  I  know.  Merz's  stronger  objectives, 
furnished  with  a  correcting  apparatus,  have  received  well- 
merited  recognition  through  Ilarting  and  M.  Schultze. 
Another  renowned  Munich  establishment  is  that  of  Mr.  Bader. 
His  smaller  instruments  cost  45  guldens. 

Zeiss,  of  Jena,  has  also  supplied  compound  microscopes  for 
some  time.  Several  years  since,  Schacht  and  M.  Schultze  gave 
us  accurate  information  concerning  these  instruments,  bestow- 
ing upon  them  the  highest  praise.  Zeiss  has,  at  present,  eight 
different  efficient  stands,  varying  in  price  from  8  to  55  thalers. 
His  objectives  are  distinguished,  according  to  their  strength,  by 
the  letters  A  to  F.  The  first  costs  5  thalers,  and  the  following 


TESTING    THE    MICROSCOPE.  79 

ones  from  7  to  18  thalers ;  No.  F.  is  reckoned  at  25  thalers.  All 
of  liis  objectives  with  which  I  have  been  latterly  acquainted 
are  very  well  constructed.  No.  F.  is  such  a  strong  and  excellent 
combination  that  one  ntrely  requires  to  use  one  of  greater 
power. 

In  Wetzlar,  about  1840,  C.  Kellner  supplied  instruments 
which  were  excellent  for  that  time.  His  immediate  successors, 
Belthle  and  Rexroth,  have  in  their  price-currents  microscopes 
from  35  to  120  thalers.  Belthle  showed  me  good  instruments 
years  ago.  Since  Belthle's  death,  the  business  has  passed  into 
the  hands  of  Leitz.  His  productions  merit  entire  recognition. 
Another  establishment  in  the  same  place  is  that  of  Engelbert  & 
Ilensoldt.  Their  instruments  are  likewise  very  good. 

Moller  and  Emmerich,  of  Giessen,  have  supplied  microscopes 
for  several  years. 

In  Hamburg,  Schroder  (Holland ischer  Brook  No.  31),  has 
made  himself  a  name  as  a  microscope-maker.  A  strong  im- 
mersion objective,  with  apparatus  for  correction,  which  I  tested 
several  years  since,  was  good,  but  ranked  considerably  below 
Hartnack's.  The  angle  of  aperture  is  large  in  his  strongest 
objectives.  The  price  of  the  stands  is  from  12  to  60  thalers. 
The  objectives  cost  from  14  to  20  thalers.  Immersion  lenses 
cost  from  20  to  32  thalers. 

Hasert  has  made  his  appearance  in  Eisenach  as  a  microscope- 
maker.  He  has  produced  very  strong  immersion  systems  which 
have  been  very  highly  praised  by  several  for  oblique  illumi- 
nation. 

F.  W.  Schiek  (Halie'sche  Strasse  No.  14)  is  the  oldest  firm 
in  Berlin.  Some  of  his  productions,  which  I  have  recently 
seen,  were  equal  to  any  made  at  the  present  time,  being  very 
good,  at  a  moderate  price.  The  stands  and  objectives  resemble 
those  of  Ilartnack  in  form  and  designation.  Microscopes 
costing  from  38  to  G5  thalers  may  be  recommended  as  being 
very  suitable  for  students  and  physicians.  Strong  objectives, 
some  of  them  of  gigantic  strength,  and  deserving  of  great  praise, 
have  issued  from  another  workshop,  that  of  E.  Gundlach, 
in  the  same  city.  I  have  also  seen  some  beautiful  and  very 
recent  productions  by  Beneehe  (Belle  Alliance  Strasse  No.  33) 


80  SECTION   FOURTH. 

I  mention,  finally,  one  other  firm,  that  of  Schmidt  &  Hansch 
(Dragoiier  Strasse  No.  19). 

Robert,  of  Barth,  in  Pomerania,  is  to  be  mentioned  as  a  micro- 
scope-maker. Unfortunately  I  am  not  acquainted  with  any  of 
his  instruments. 

S.  Plossl  (alte  Wieden,  Theresianumgasse  No.  12)  was  the 
first  maker  in  Vienna.  Nearly  thirty  years  ago  Plossl's  micro- 
scopes were  reckoned  among  the  best  which  were  known.  Lam 
unable  to  give  any  information  regarding  his  later  productions. 
The  present  address  is  Plossl  &  Co. 

The  excellent  instruments  of  Amici,  of  Italy,  have  obtained 
great  renown.  They  were  the  best  Continental  microscopes 
from  1840  to  1850,  the  deceased  Amici  having  at  that  time 
acquired  the  greatest  merit  in  the  construction  of  improved 
microscopes.  I  know  nothing  further  of  his  instruments  pro- 
duced more  recently. 

The  three  most  renowned  London  firms  are  :  Powell  &  Lea- 
land  (170  Euston  road),  Andrew  Ross  (7  Wigmore  street,  Ca- 
vendish square,  "W.),  continued,  since  the  death  of  the  founder, 
by  the  son,  Thomas  Ross,  and  Smith,  Beck  &  Beck  (6  Coleman 
street).  Among  the  remainder  we  will  also  mention  Pillischer 
(2  New  Bond  street),  "VV.  Highley  (70  Dean,  street,  Soho  square 
10),  and  Baker  (44  High  Holborn).  It  is  highly  commendable 
that,  for  a  series  of  years,  the  English  have  endeavored  to  pro- 
duce instruments  which  might  be  as  cheap  as  possible  and,  at 
the  same  time,  good.  Thus,  for  example,  a  number  of  estab- 
lishments furnish  very  fine  instruments  even  for  £5,  as 
Pillischer,  Smith,  Beck  &  Beck. 

Among  the  microscope-makers  of  North  America,  the  most 
important  are  Spencer,  Tolles,  and  "W.  Wales.  Zentmayer  has 
recently  produced  very  good  stands.  The  optical  perform- 
ances do  not  surpass  those  of  our  best  European  instruments  ; 
the  prices,  however,  are  enormous  (H.  Hagen). 

[The  history  of  the  microscope  as  an  American  instrument 
commences  at  a  very  recent  date. 

I  am  informed  by  Mr.  T.  H.  McAllister,  optician  of  this  city, 
that  in  the  year  1840,  when  the  United  States  Exploring  Ex- 
pedition to  the  South  seas,  under  Commodore  "Wilkes,  was 


TESTING    THE    MICROSCOPE.  81 

fitting  out,  it  was  thought  necessary  to  have  a  microscope.  It 
was  then  discovered  that  none  was  to  be  had.  The  various 
makers  of  scientific  and  philosophical  instruments  were  applied 
to,  but  none  of  them  could  furnish  the  expedition  with  the 
desired  microscope.  In  this  dilemma  a  private  individual  was 
applied  to,  and  an  instrument  was  finally  obtained  from  Dr. 
Paul  Goddard,  of  Philadelphia.  It  was  a  French  microscope, 
which  would  now  be  considered  very  inferior,  but  was  the  best 
instrument  then  to  be  had  in  this  country. 

Since  that  time  the  instrument  has  come  into  general  use, 
and  in  certain  departments  of  the  manufacture  of  microscopes 
this  country  has  become  pre-eminent.  Scarcely  had  the  English 
microscope-makers  published  those  inventions  and  discoveries 
which  rendered  achromatic  microscopes  really  possible,  and 
elevated  the  instrument  from  the  position  of  a  mere  scientific 
plaything  to  that  of  an  instrument  calculated  for  the  most 
accurate  investigations,  before  Charles  A.  Spencer,  of  this  State, 
succeeded  in  producing  lenses  which  at  once  took  a  front  rank 
among  the  art  productions  of  the  world.  Spencer  and  his 
pupil  Tolles,  also  Wales,  Grunow,  Zentmayer,  and  perhaps  a  few 
others,  have  since  that  time  kept  up  the  reputation  of  the 
American  lenses,  and  to-day  there  is  no  country  in  the  world 
in  which  are  produced  finer  object  glasses  than  those  of  domes- 
tic make. 

Previous  to  Spencer's  time,  some  few  microscopes  and  objec- 
tives had  been  constructed  by  amateurs,  but  their  authors  have 
never  become  celebrated  in  this  department. 

Spencer  was  induced,  while  still  a  lad,  by  the  perusal  of  the 
article  on  optics  in  the  "  Edinburgh  Encyclopaedia,"  to  construct 
a  compound  microscope.  His  first  lens  was  made  when  he  was 
about  twelve  years  of  age ;  this  first  attempt  was  followed  by 
others,  at  intervals,  during  subsequent  years.  After  making 
several  compound  microscopes,  and  a  refracting  one  upon  the 
original  plan  of  Prof.  Amici,  he  constructed  several  Gregorian 
and  Newtonian  telescopes  with  specula  of  six  and  eight  inches 
diameter,  some  of  which  were  quite  successful. 

It  was  not  till  the  publication  of  the  "  Penny  Magazine  "  and 

the  "Library  of  Useful  Knowledge,"  however,  that  he  became 
6 


82  SECTION    FOURTH. 

aware  of  the  improvements  which  had  been  made  in  Paris  and 
London  in  the  achromatic  microscope.  The  results  obtained  by 
Goring  and  Pritchard  in  both  the  achromatic  and  reflecting 
microscopes  excited  his  attention  especially.  The  discovery  by 
the  former  of  the  effects  of  angle  of  aperture  was  a  powerful 
inducement  for  Spencer  to  perfect  himself  more  thoroughly  in 
this  branch  of  optical  science.  About  this  time  he  also  learned 
of  the  successful  researches  of  Guinaud,  Fraunhofer,  and  Fara- 
day in  the  manufacture  of  optical  glass.  By  laborious  and  pro- 
tracted experiments,  frequently  working  over  the  furnace  for 
eighteen  consecutive  hours,  he  succeeded  in  improving  the 
homogeneousness  and  other  qualities  of  the  glass  considerably, 
which  enabled  him  to  make  an  evident  advance  upon  his  pre- 
vious efforts  in  constructing  lenses. 

A  few  instruments  were  made  for  personal  friends,  but  it  was 
not  till  later,  about  1847,  that  Spencer  became  a  professional 
microscope-maker.  About  this  time  he  visited  New  York  City, 
and  was  introduced  by  Dr.  John  Frey  to  the  late  Prof.  C.  R. 
Gilman.  Dr.  Gilman  had  a  microscope,  constructed  by  Cheva- 
lier, of  Paris,  which  he  showed  to  Spencer  and  induced  him  to 
make  one  like  it.  The  result  was,  that  Prof.  G.  sold  his  Cheva- 
lier instrument  and  replaced  it  with  the  one  made  by  Spencer. 
This  instrument  was  completed  in  November,  1847.  In  bring- 
ing it  to  New  York,  Mr.  Spencer  stopped  at  West  Point,  and 
showed  his  microscope  to  the  late  Prof.  Bailey,  then  the  ac- 
knowledged chief  of  microscopical  observers  of  this  country. 
It  was  with  this  instrument  that  Prof.  Bailey  resolved  the  Na- 
vicula  Spencerii,  noticed  in  the  first  edition  of  Quekett  on  the 
Microscope.  This  author,  at  page  440,  in  speaking  of  the  N. 
Spencerii,  says:  "that  an  object  glass,  constructed  by  a  young 
artist  of  the  name  of  Spencer,  living  in  the  backwoods,  had 
shown  three  sets  of  lines  on  it,  when  other  glasses  of  equal 
power,  made  by  the  first  English  opticians,  had  entirely  failed 
to  define  them." 

The  information  which  Quekett's  treatise  contained  concern- 
ing the  discoveries  of  Lister  and  the  labors  of  Amici  and  Ross, 
was  extremely  useful  to  our  "  Yankee  backwoodsman."  In  the 
account  given  of  Ross's  discovery  of  the  effect  of  thin  glass 


TESTING    THE    MICKOSCOPE.  83 

covers  upon  the  correction  of  an  objective,  the  announcement 
was  made  that  "on  several  occasions  the  enormous  angle  of  135° 
had  been  obtained,"  and  that,  "  135°  is  the  largest  angular  pen- 
cil that  can  be  passed  through  a  microscopic  object  glass." 
This  statement,  coming  from  a  source  so  generally  considered 
authoritative,  arrested  Spencer's  attention  and  led  to  an  imme- 
diate theoretical  and  practical  examination  of  its  validity. 
The  supposed  theoretical  grounds  of  the  assumption  not 
having  been  found  to  sustain  Mr.  Hoss's  position,  conclusive 
evidence  of  its  incorrectness  was  speedily  obtained  by  the 
construction  of  a  r^  in.  objective,  having  an  angle  of  aperture 
of  146°. 

An  increase  of  the  angle  of  aperture  of  the  higher  powers 
had  been  made  from  time  to  time,  until  the  maximum  angle  of 
178°,  for  the  j1^,  was  obtained  in  June,  1851;  and  subsequently 
the  medium  and  lower  powers  were  correspondingly  improved. 
An  investigation  into  the  practicability  of  so  far  increasing  the 
defining  and  resolving  powers  of  the  objectives  of  medium 
focal  lengths  was  made,  and  results  have  been  obtained  which 
could  not,  d  j}rioriyli&\c  been  expected.  The  angle  of  aperture 
of  the  \  has  been  increased  to  175°,  and  its  defining  and  resolv- 
ing powers  are  such  that  it  bears  oculars  bringing  its  amplify- 
ing powers  up  to  twelve  hundred  diameters,  without  any  con- 
siderable deterioration  in  the  sharpness  of  its  images.  With  it 
the  19th  band  of  Robert's  test  plate  has  been  resolved  by 
Spencer  with  ordinary  daylight  illumination  and  with  artificial 
light.  The  residual  errors  have  been  the  subject  of  continued 
investigation  since  then,  and  they  afford  an  ample  field  for  the 
exercise  of  the  highest  mental  powers  and  manual  skill. 

We  have  now  to  speak  of  another  Automath,  Mr.  J.  Grunow, 
who  came  from  Berlin  to  this  country  in  1849,  and  settled  in 
New  Haven,  Conn.  He  was  induced  by  Drs.  Henry  Yan  Ars- 
dale  and  C.  R.  Oilman  to  study  optics  and  to  commence  the 
manufacture  of  microscopes.  Grunow  was  his  own  teacher, 
and  had  been  engaged  in  an  entirely  different  business  previous 
to  his  arrival  in  this  country.  lie  constructed  his  first  micro- 
scope for  Dr.  Yan  Arsdale  in  1852,  and  soon  afterwards  a 
second  one  for  Prof.  Oilman.  About  this  time  Gruuow's 


84  SECTION    FOTJKTH. 

brother  became  associated  with  him  and  constructed  the  stands, 
which  were  models  of  good  workmanship. 

It  may  be  interesting  in  this  connection  to  remark  that  Prof. 
Riddell  of  this  country,  the  inventor  of  the  binocular  micro- 
scope, used  for  his  experiments  in  this  direction  prisms  made 
by  Fitz,  of  New  York.  The  first  binocular  microscope,  how- 
ever, was  constructed  for  Prof.  H.  in  1853,  by  Grunow. 

A  very  valuable  improvement,  made  by  Grunow,  consists 
in  letting  the  rotary  diaphragm  into  the  upper  surface  of  the 
(immovable)  stage  in  such  a  manner  that  it  is  just  below  the 
level  of  the  same,  and  can  be  rotated  without  disturbing  the 
slide  on  which  the  object  is  placed.  In  this  way  the  full  opti- 
cal effect  of  the  diaphragm  is  obtained  exactly  at  the  point 
where  it  is  needed. 

Mr.  E,.  B.  Tolles  became  a  pupil  of  Spencer  in  1843.  In  1856 
he  commenced  business  for  himself,  and  after  several  years  re- 
moved to  Boston,  Mass. 

Mr.  Tolles  is  the  author  of  a  number  of  valuable  improvements 
in  microscopical  accessories  ;  among  these  his  stereoscopic  bino- 
cular and  solid  eye-pieces,  his  method  of  adjusting  for  cover  by 
making  the  front  lens  stationary  and  no  back  lash,  as  well  as  his 
method  of  making  two  fronts  to  an  objective — one  immersion, 
and  one  dry — deserve  especial  mention.  The  excellent  quality 
of  his  objectives  has  earned  him  a  world-wide  reputation. 

Mr.  J.  Zentrnayer,  of  Philadelphia,  was  introduced  to  the 
American  microscopic  public  by  Mr.  T.  II.  McAllister.  The 
first  instrument  which  he  made  was  for  Dr.  Paul  Goddard,  of 
that  city,  in  the  year  1858.  This  instrument  is  now  in  the  pos- 
session of  Dr.  Squibb,  the  Chemist,  of  Brooklyn,  N.  Y.,  and  is 
almost  identical  with  the  present  "  Grand  American  Stand." 

Zentmayer  is  the  inventor  of  several  valuable  improvements 
in  microscopical  accessories,  which  will  be  mentioned  in  the 
price-list  at  the  end  of  this  book.  The  elegant  workmanship  of 
his  stands  is  unsurpassed  by  those  of  any  other  maker. 

Mr.  Win.  Wales  was  a  pupil  of  Smith  and  Beck,  in  London. 
He  came  to  this  country  about  1862.  After  remaining  here  for 
a  few  months  he  went  back  to  England,  but  soon  returned  to 
Fort  Lee,  N.  J.  Since  this  time  his  lenses  have  constantly  im- 


TESTING    THE    MICROSCOPE.  85 

proved  in  quality,  and  are  considered  by  many  competent  judges 
to  be  equal  to,  if  they  do  not  excel,  those  of  any  other  maker  in 
the  world. 

Mr.  L.  Miller  was  formerly  in  the  employ  of  Tolles,  but  com- 
menced business  for  himself  in  1868.  Some  of  his  lenses  which 
I  have  seen  were  very  good. 

In  addition  to  the  firms  above  mentioned,  there  are  three 
others  who  also  furnish  very  excellent  instruments ;  namely, 
Messrs.  McAllister,  Pike,  and  Queen. 

The  microscopes  made  in  this  country  are  generally  to  supply 
the  home  demand,  and  but  few  have  been  exported.  Some  have 
found  their  way  to  Europe,  where  they  have  been  critically  ex- 
amined by  the  French  and  English  makers,  and  various  impor- 
tant improvements,  which  originated  with  American  makers, 
have  been  appropriated  by  them.  For  instance,  in  "  Carpenter 
on  the  Microscope,"  London,  1868,,  will  be  found,  on  page  68,  a 
description  of  a  piece  of  microscopic  apparatus,  invented  by 
Zentmayer  in  1862,  but  which  was  copied  by  a  Paris  maker,  to 
whom  Dr.  Carpenter  gives  the  credit  of  being  the  inventor. 

In  speaking  of  this  instrument  (Cachet's  student's  microscope) 
Dr.  Carpenter  says : — "  The  chief  peculiarity  of  this  instrument, 
however,  lies  in  the  stage,  which  the  author  has  no  hesitation  in 
pronouncing  to  be  the  most  perfect  of  its  kind  that  has  yet  been 
devised."  The  instrument  from  wrhich  Nachet  copied  the  circu- 
lar stage  was  made  by  Zentmayer  in  1864  for  Dr.  "W.  "W.  Keen, 
of  Philadelphia,  who  showed  it  three  different  times  to  M. 
Nachet,  and  had  it  packed  by  him,  in  the  spring  of  1865,  for 
transportation. 

The  American  microscopes  are  characterized  by  extreme 
simplicity,  combining  all  that  is  necessary  for  a  good  working 
instrument,  and  rejecting  numerous  complicated  movements  and 
much  superfluity  of  workmanship  which  some  foreign  makers 
seem  to  consider  essential. 

The  form  of  stand  which  has  found  most  favor  in  this  country 
is  the  one  devised  by  Mr.  G.  Jackson,  of  London.  It  consists 
mainly  of  a  stout  bar  which  carries  the  body,  stage,  accessory 
box,  and  mirror;  securing  steadiness,  equal  distribution  of 
tremor,  and  facilitating  the  centring  of  the  accessories  and 


86  SECTION   FOURTH. 

achromatic  illumination.  It  will  be  found,  on  examination, 
that  modifications  of  this  principle  have  been  applied  in  nearly 
all  of  our  American  microscopes. 

As  complete  descriptions  of  the  various  instruments,  objec- 
tives, and  accessories  will  be  found  in  the  price-lists  of  the  dif- 
ferent makers,  at  the  end  of  this  book,  it  is  unnecessary  to  allude 
to  them  in  this  place. 

Microscopes  of  American  manufacture,  from  their  compara- 
tive cheapness — to  the  cost  of  importation  must  be  added  the 
duty,  which  is  45  per  cent,  ad  valorem — and  the  facility  with 
which  they  can  be  procured,  offer  inducements  to  students  and 
others  to  procure  their  instruments  at  home,  and  thus  save  time 
to  themselves,  at  the  same  time  that  they  stimulate  the  manufac- 
turers to  make  increased  efforts  to  attain  even  greater  excel- 
lence.] 


0cction  liftl). 


USE  OF  THE  MICROSCOPE.—  MICROSCOPIC  EXAMINATION. 

PRACTICAL  directions  for  learning  to  work  with  the  microscope 
may  be  given  pretty  rapidly  and  without  difficulty,  while  it  is 
painfully  troublesome  for  the  beginner  to  acquire  this  from 
written  instructions.  We  shall  therefore  limit  ourselves  to 
rendering  some  of  the  chief  points  prominent,  and  must  leave 
many  other  things  for  the  microscopist  to  study  out  for  himself. 

Suitable  illumination  is  of  great  value  for  microscopic  work. 
As  most  examinations  are  made  with  transmitted  light,  and  the 
application  of  natural  light  is,  in  this  case,  to  be  preferred  to 
any  artificial  illumination,  the  selection  of  a  working  room  is 
not  a  matter  of  indifference.  When  possible,  one  should  be 
selected  which  lies  towards  the  northwest  or  northeast,  and 
affords  an  outlook,  so  that  a  larger  portion  of  the  sky  may  be 
used  for  the  reception  of  the  rays  of  light.  In  the  narrow 
streets  of  cities,  only  the  upper  stories  of  the  houses  can 
generally  be  used.  It  is  convenient  to  have  windows  on  two 
sides  of  the  room  ;  but  those  of  the  side  opposite  to  the  windows 
which  are  in  use  should  be  closed  by  a  dark  curtain  or  shutters. 

For  ordinary  investigations,  one  may  without  disadvantage 
place  the  instrument  011  a  table  standing  near  the  window,  and 
thus  make  the  preparations  and  examine  them  on  one  and  the 
same  table.  But  when  the  best  possible  illumination  is  required, 
such  a  position  should  not  be  selected  for  the  microscope ;  the 
instrument  should  be  placed  at  a  considerable  distance,  from  six 
to  nine  feet  or  more,  from  the  window.  A  dark  shade,  which 
can  be  placed  over  the  stage  by  means  of  a  ring  fastened  to  the 
microscope  tube,  will  shut  off  all  incident  light  from  the  object, 
and  essentially  improve  the  image.  Such  shading  of  the  stage 
should  never  be  neglected  when  making  observations  with  po- 


88  SECTION    FIFTH. 

larized  light,* or  resolving  very  difficult  test  objects  with  oblique 
illumination. 

The  condition  of  the  sky  is  of  importance  for  the  illumination. 
A  clear  blue  sky  gives  a  very  fine,  soft  light  which  does  not  tire 
the  eye,  and  is  sufficiently  bright  for  all  but  the  very  strongest 
objectives.  A  dull,  white,  uniform  cloudiness  is  still  more  pref- 
erable. Bright  white  clouds,  which  lie  near  the  sun,  should  not 
be  selected,  on  account  of  their  dazzling  light.  The  rapid  pass- 
ing of  white  clouds  over  a  blue  sky,  when  the  atmosphere  is 
strongly  agitated,  is  very  unpleasant  and  troublesome.  When 
the  sun  shines  through  the  window,  a  white  curtain  drawn  over 
it  or  lowered  from  a  roller  is  of  service. 

To  illuminate  the  field,  the  microscope  is  turned  towards  the 
window,  and  the  mirror  is  rotated  and  moved  with  one  hand, 
while  the  observer  is  looking  through  the  instrument.  When 
the  best  light  has  thus  been  found,  the  object  to  be  examined  is 
placed  on  the  stage  of  the  microscope  and  the  further  correction 
of  the  field  is  commenced ;  for  example,  lowering  the  cylindrical 
diaphragm  or  slightly  altering  the  position  of  the  mirror,  the 
object  being  constantly  kept  in  sight.  When  the  mirror  is  freely 
movable  it  is  unnecessary  to  alter  the  position  of  the  instrument ; 
but  the  limited  movement  of  the  mirror  which  many  of  the 
smallest  microscopes  permit,  often  requires  a  turning  and  mov- 
ing of  the  microscope. 

The  beginner  generally  thinks  that  he  can  accomplish  most 
with  a  brightly  illuminated  field,  and  thus  he  works,  dazzled  by  a 
sea  of  light,  with  weeping,  rapidly  tiring  eyes.  The  experienced 
observer  is  accustomed,  as  a  rule,  to  diminish  the  intensity  of  the 
light  considerably.  Together  with  the  protection  of  the  organ 
of  vision,  it  is  only  in  this  way  that  the  finest  details  of  the 
microscopic  image  can  be  perceived.  The  skilful  application 
of  the  illuminating  apparatus  and  the  use  of  the  diaphragm 
should  therefore  at  once  be  practised  by  the  beginner  as  much 
as  possible.  Wlien  the  instrument  has  a  mirror  with  plane  and 
concave  surfaces,  the  former  is  used  with  the  weaker  objectives 
and  a  bright  light,  the  latter  with  the  stronger  objectives  and  a 
light  which  is  less  intense.  A  very  perceptible  deficiency  is 
always  connected  with  instruments  not  having  such  an  arrange- 


USE    OF   THE    MICROSCOPE. 


89 


ment.  This  may  be  remedied  in  a  measure,  it  is  true,  by  turn- 
ing the  microscope,  or  by  holding  the  hand  in  certain  positions 
before  it. 

Considerable  practice  is  requisite  with  the  oblique  illumina- 
tion (fig.  61).  The  aperture  of  the  stage  must  be  freed  from 
diaphragms,  or  any  other  apparatus  which  may  be  under  the 
stage,  and  the  various  positions  of  the  mirror  are  to  be  tried 
while  the  eye  is  looking  into  the  microscope.  At  the  same  time, 
wiiile  the  mirror  is  brought  up  close  beneath  the  stage,  the  illu- 
mination is  made  as  oblique  as  possible.  Truly  diabolical 
illumination  is  thus  sometimes  obtained,  which,  however,  shows 
many  fine  details  in  an  as- 
tonishing manner.  When 
the  microscope  has  a  well- 
centred  rotary  stage,  its  rota- 
tion is  of  great  importance 
with  this  illumination.  An 
observer  who  is  familiar 
with  his  instrument  and  well 
versed  in  this  department  of 
microscopical  technology, 
will  be  able  to  show  many 
things,  to  the  astonishment 
of  the  unpractised  investi- 
gator, which  the  latter  was 
unable  to  accomplish  after 
hours  of  unsuccessful  labor. 
The  resolution  of  the  systems 
of  lines  of  the  Pleurosigma  angulatum  into  areolations,  with 
strong  objectives,  and  the  exhibition  of  the  markings  of  the 
Surirella  gemma  and  Grammatophora  subtilissima  by  means  of 
the  strongest  immersion  lenses,  may  be  designated  as  specimens 
of  the  art  of  oblique  illumination.  This  is,  however,  only  of 
minor  value  for  our  purposes. 

No  one  should  make  any  protracted  microscopic  investigations 
by  the  aid  of  the  artificial  light  of  a  lamp  or  gas  flame  if  he 
can  possibly  avoid  it,  or  would  spare  his  eyes.  In  Northern 
Europe,  during  the  winter,  there  are  days  when  the  natural  light 


Fig.  61.    Oblique  position  of  the  mirror  on  the 
horse-shoe  stand. 


90 


SECTION    FIFTH. 


is  entirely  unserviceable,  and,  vexed  by  the  miserable  light,  one 
finally  has  recourse  to  artificial  illumination.  When  it  is  neces- 
sary to  resort  to  artificial  light,  an  ordinary  moderatQur^  which 
should  not  be  too  high,  an  Argaud  or  a  petroleum  lamp,  with  a 
globe  of  opalescent  glass,  is  worthy  of  re- 
commendation. A  petroleum  lamp  (fig. 
62)  provided  with  a  large  condensing  lens, 
recently  constructed  by  Ilartnack,  is  very 
convenient;  it  should  also  have  a  shade. 
Properly  constructed  gas  lamps  may  also 
be  employed  with  advantage.  A  number 
of  these,  with  very  j  udicious  arrangements, 
have  been  invented  and  recommended  by 
English  microscopists. 

A  proper  moderation  of  the  light  is  here 
urgently  necessary.  The  illumination  may 
be  essentially  improved  by  placing  a  co- 
balt-blue glass  of  greater  or  lesser  intensity 
f between  the  lamp  flame  and  the  object. 
It  may  be  placed  011  the  mirror  or,  better, 
on  the  stage.  A  black  pasteboard  screen 
with  apertures  of  various  sizes,  which  may 
be  placed  in  front  of  the  microscope 
parallel  with  the  mirror,  and  on  which  the 
blue  glass  may  be  fastened  with  wax,  forms  a  cheap  accom- 
paniment of  the  large  Oberhauser-IIartnack  microscope,  and 
deserves  to  be  highly  recommended  for  its  important  action.  A 
rotary  diaphragm  should  be  placed  behind  the  screen.  In  place 
of  the  above  blue  glasses  of  various  sorts,  which  can  be  shoved 
into  a  metallic  ring,  may  be  inserted  into  the  stage,  as  neces- 
sity may  require.  Such  an  arrangement  may  be  readily  applied 
to  all  of  the  larger  stands. 

[A  very  ingenious  arrangement  of  the  illumination  has  been 
contrived  by  my  friend  Dr.  Edward  Curtis,  of  this  city. 

A  small  lamp,  similar  to  the  one  represented  in  fig.  62,  is 
placed  in  a  cigar-box,  which  stands  on  one  of  its  ends.  On  one 
side  of  the  box  is  cut  a  small  aperture,  in  which  is  placed  a 
piece  of  blue  glass,  to  soften  the  light  as  it  passes  to  the  micro- 


rip.  62.  Hartnack's  micro- 
scope lamp. 


USE    OF    THE    MICROSCOPE.  91 

scope  mirror.  Another  larger  opening  is  made  in  the  front  of 
the  box  and  is  occupied  by  three  different  glasses.  The  one 
nearest  the  lamp  is  a  square  piece  of  ground  glass ;  the  next  one 
is  also  square  and  flat,  but  colored  blue.  Finally,  a  plano-con- 
vex glass  lens  of  long  focus  is  placed  at  such  an  inclination  as 
to  condense  the  rays  of  light,  thus  softened,  on  to  the  work-table 
for  use  in  dissecting  or  arranging  preparations.] 

Although  direct  sun  and  lamp  light  is  to  be  entirely  rejected 
for  ordinary  investigations,  these  most  intense  of  all  illuminating 
methods  must,  on  the  contrary,  be  selected  for  many  investiga- 
tions with  polarized  light.  Opaque  objects  require  illumination 
by  incident  light  with  seclusion  from  transmitted  rays.  Ordi- 
nary daylight  is  sufficient  for  very  weak  powers;  writh  stronger 
ones,  more  intense  illumination  is  necessary.  Sunlight  may  be 
used  in  certain  cases.  Numerous  contrivances  are  in  use  for 
concentrating  the  light  on  the  object.  A  plano-convex  lens  of 
large  focus  (fig.  21),  which  is  placed  before  the  instrument,  is 
generally  sufficient ;  this  may  also  be  accomplished  with  a  glass 
prism.  Lieberkiihn's  illuminating  apparatus  also  deserves 
mention  as  a  good  and  very  suitable  contrivance,  although  it  is 
rarely  employed  in  medical  investigations. 

The  object  to  be  examined  will  have  to  undergo  a  preliminary 
preparation,  if  it  be  not  already  a  permanent  preparation.  This 
process,  which  naturally  varies  considerably  according  to  cir- 
cumstances, generally  rendering  the  examination  possible  with 
transmitted  light,  however,  we  shall  soon  treat  more  in  detail. 
Let  the  remark  here  suffice,  that  the  preparation  is  to  be  made 
with  care  and  the  observance  of  the  greatest  cleanliness ;  and 
then,  on  the  other  hand,  we  would  say,  not  to  do  too  much  of  a 
good  thing,  that  is,  not  to  select  too  large  pieces  for  examina- 
tion. Beginners  fail  in  this  very  generally,  and  place  under 
the  microscope  masses  which,  divided,  would  have  furnished  a 
dozen  serviceable  preparations.  One  rarely  examines  with  in- 
cident light  alone,  in  which  case  the  object  can  be  placed  un- 
covered and  dry  on  the  stage  of  the  microscope.  As  a  rule,  it 
is  necessary  to  moisten  the  preparation  (with  water,  preserving 
fluids,  glycerine,  etc.,  see  below).  With  weak  powers  the  ob- 
ject may  still  remain  uncovered,  and,  in  fact,  many  things  are 


92  SECTION   FIFTH. 

thus  examined,  although  the  preparation  is  generally  placed  in 
a  watch-glass,  a  glass  box,  or  a  cell,  instead  of  on  a  simple  slide. 

If,  however,  one  has  recourse  to  higher  powers,  it  will  be 
necessary  to  cover  the  object  with  a  plate  of  glass.  This  should 
be  thin,  and  as  clean  as  possible.  All  fluids  must  be  prevented 
from  running  over  its  free  surface,  as  the  image  becomes  some- 
what dim  and  indistinct  with  ordinary  objectives,  although,  as 
previously  mentioned,  with  the  new  immersion  systems  a  drop 
of  water  must  be  placed  on  the  upper  surface  of  the  covering 
glass.  In  the  application  of  the  covering  glass,  all  contact  of 
its  surfaces  with  the  fingers  is  to  be  avoided;  held  by  its  sides, 
it  is  to  be  laid  over  the  object.  Some  caution  is  necessary  with 
very  delicate  objects;  for  example,  a  primitive  mammalial  ovum 
might  be  crushed  by  covering  it  awkwardly ;  the  elements  of  the 
fresh  retina  might  have  their  connection  destroyed,  etc.  Simple 
contrivances  serve  for  the  protection  of  such  preparations ;  a 
piece  of  hair  or  bristle,  or  the  fragment  of  a  thin  film  of  glass, 
may  be  placed  between  the  slide  and  the  covering  glass. 

The  adjustment  is  made,  while  looking  through  the  micro- 
scope, by  sinking  the  tube.  This  is  done  either  by  simply 
shoving  it  down  through  its  sheath  with  the  hand,  or,  when 
there  is  a  coarse  screw,  by  moving  it  downwards  with  the  latter. 
In  doing  this,  thrusting  the  lens  against  the  preparation  is  to  be 
avoided,  because  the  latter  may  be  spoiled  and  its  covering  glass 
broken,  and  in  certain  cases  the  lens  may  also  be  injured.  It  is 
well  for  beginners  to  make  this  movement  in.  the  contrary  di- 
rection, that  is,  elevating  instead  of  depressing  the  tube,  which 
is  to  be  so  adjusted  that  there  is  only  a  small  space  between  the 
covering  glass  and  the  lens,  and  then  moved  upwards.  Accu- 
rate adjustment  requires  some  practice,  and  is  not  very  easy 
with  strong  objectives.  That  the  correct  adjustment  has  been 
made,  is  shown  when  the  contours  of  the  object  are  sharpest 
and  finest.  Here  the  fine  adjusting  screw  comes  in  play. 

The  preparation  is  to  be  first  examined  with  low  powers  and 
transmitted  central  light,  gradually  passing  to  higher  powers ; 
very  weak  eye-pieces  being  constantly  employed.  In  some  cases 
the  tube  of  the  microscope  may  be  shortened  with  advantage. 

[The  changing  of  the  objectives  is  facilitated  by  the  employ- 


USE    OF   THE    MICROSCOPE.  93 

ment  of  a  "  nose-piece."  This  is  an  apparatus  having  two  or 
more  arms  capable  of  revolving  and  carrying  the  objectives  at 
their  peripheral  extremities.  The  mechanism  is  to  be  screwed 
on  to  the  lower  end  of  the  microscope  tube,  the  same  as  a  simple 
objective.  The  various  objectives  are  brought  into  position 
successively  by  simply  turning  the  arms.  Further  movement 
and  accurate  centring  is  controlled  by  means  of  a  catch.  The 
original  "  nose-piece,"  invented  by  Brooke,  of  London,  revolved 
on  a  horizontal  plane,  but  by  a  more  recent  improvement  the 
objectives  which  are  not  in  use  are  elevated  obliquely,  and  only 
become  vertical  at  the  moment  they  are  adj  usted  to  the  axis  of 
the  microscope  tube,  so  that  they  do  not  in  any  manner  interfere 
with  the  manipulation  of  the  stage.  This  accessory  is  almost 
indispensable  for  those  who  work  much  with  the  microscope.] 

It  is  a  general  mistake  of  beginners,  who  under-estimate  the 
value  of  low  powers,  to  use  high  powers  at  the  very  commence- 
ment of  the  examination.  As,  however,  only  the  weak  ob- 
jectives afford  a  somewhat  extended  field  of  vision,  while  with 
stronger  lenses  it  is  extremely  small,  it  results  that  the  employ- 
ment of  weak  combinations  is  of  great  importance  for  the  si- 
multaneous survey  of  the  whole,  as  well  as  to  give  the  observer 
the  first  ideas  as  to  the  relation  of  its  several  parts. 

One  then  gradually  passes  to  the  employment  of  stronger 
objectives;  at  first,  always  with  very  weak  eye-pieces.  When 
working  with  cylindrical  diaphragms  it  is  necessary  to  vary 
them,  exchanging  those  with  large  apertures  for  those  with 
smaller  ones,  likewise  occasionally  exchanging  the  plane  mirror 
for  the  concave,  and  in  all  cases  adjusting  as  accurately  as  pos- 
sible with  the  micrometer  screw. 

When  the  observer  has  found  it  necessary  to  make  use  of  his 
higher  powers,  he  may  proceed  to  employ  somewhat  stronger 
eye-pieces ;  but  he  should  be  sparing  in  their  use.  One  is  soon 
convinced  that  less  is  obtained  with  them,  which  results  from 
their  optical  nature,  than  would  be  at  first  believed.  The  image 
is  larger,  whereby  some  points  may  at  first  appear  more  distinct. 
An  enlargement  is  soon  arrived  at,  however,  which  does  not 
show  any  more,  but  rather  less,  than  the  weaker  of  the  previously 
employed  eye-pieces,  the  brightness  of  the  field  and  the  sharp- 


94  SECTION   FIFTH. 

ness  of  the  image  having  considerably  diminished.  Very  strong 
eye-pieces,  which  are  added  to  the  larger  instruments  as  an 
optical  supplement,  are  articles  of  luxury,  and  are  scarcely  of 
any  use. 

Objectives  which  are  well  made  as  to  their  optical  portions 
bear  stronger  eye-pieces  than  those  which  are  less  fortunate  in 
their  construction.  Nevertheless,  even  in  this  case,  one  should 
be  careful  of  forcing  the  magnifying  power  by  means  of  the 
eye-piece.  The  latter,  it  is  true,  might  be  still  more  improved, 
and  it  is  to  be  wished  that  capable  opticians  might  turn  their 
attention  to  this  subject.  The  orthoscopic  eye-pieces  which,  so 
far  as  I  am  aware,  were  first  constructed  and  sold  by  the  un- 
fortunately so  early  deceased  Kellner,  of  Wetzlar,  give  a  very 
flat  image,  but  have  shown  me  nothing  further,  even  in  their 
stronger  numbers. 

o 

It  follows  from  what  has  just  been  said,  that  he  who  can  ob- 
tain about  the  same  magnifying  power  in  a  double  manner,  that 
is,  by  means  of  a  weak  objective  and  a  strong  eye-piece,  or  by 
means  of  a  strong  objective  and  a  weak  eye-piece,  should  always 
have  recourse  to  the  latter.  The  effort  of  the  older  opticians  to 
combine  weaker  objectives  with  relatively  stronger  eye-pieces 
cannot,  therefore, — we  repeat  it, — be  approved  of,  and  is  at 
present  being  more  and  more  abandoned. 

The  objects  of  histological  and  medical  investigations  will  sel- 
dom require  the  application  of  oblique  illumination.  If  it  be 
desired  ^o  learn  the  effects  of  the  latter,  the  directions  given 
above  are  to  be  followed. 

Wli3ii  reagents  are  to  be  vised,  it  is  customary,  as  a  rule,  to 
add  a  drop  of  them  to  the  preparation  by  means  of  a  pointed 
glass  rod,  either  by  removing  and  replacing  the  covering  glass, 
or  by  placing  the  drop  at  its  edge,  so  that  it  may  flow  under  the 
cover  and  unite  at  this  point  with  the  fluid  in  which  the  speci- 
men is  mounted.  A  gradual  streaming  in  of  the  reagent  may 
be  obtained  by  means  of  a  thread  of  lint  which  lies  half  under 
the  glass  cover,  half  free  on  the  slide  where  it  receives  the  drop. 

For  the  protection  of  the  instrument,  it  is  necessary  to  ob- 
serve due  caution  with  reagents,  especially  when  using  strong 
acids,  alkalies,  and  all  substances  which  attack  the  lead  of  the 


USE    OF   THE    MICTCOSCOPE.  95 

flint  glass.  Concentrated  muriatic  and  nitric  acids  are  to  be 
avoided  as  much  as  possible,  and  care  should  be  used  with  vol- 
atile acids  and  ammonia.  Sulphuretted  hydrogen  should  never 
be  used.  All  of  these  reagents  require  the  use  of  the  largest 
possible  covering  glasses.  If  a  lens  should  unfortunately  be- 
come moistened  with  the  reagent,  it  must  be  immediately  dipped 
into  distilled  water.  Chemical  processes  which  develop  vapors 
should  in  no  case  be  undertaken  in  the  microscopic  work-room. 
The  destructive  effects  of  such  influences  are  best  shown  by  the 
unfortunate  condition  in  which  the  microscopes  of  'chemical 
laboratories  are  usually  found. 

The  repeated  packing  and  unpacking  of  the  microscope  is  too 
troublesome  for  those  who  use  it  daily,  and  not  at  all  beneficial 
to  the  mechanism  of  the  stand.  It  is  therefore  preferable  to 
place  the  instrument  on  a  thick  piece  of  cloth,  on  the  work- 
table,  and  under  a  bell-glass  or  a  glass-case,  which  affords  suffi- 
cient protection  from  dust.  The  eye-pieces,  the  objectives  shut 
up  in  their  case,  and  such  other  things  as  are  daily  used  may  be 
kept  under  a  second  smaller  bell-glass.  It  is  advisable  to  heat 
the  room  during  the  winter,  to  prevent  dampness. 

The  instrument  should  be  re-examined  each  time  that  it  is 
used,  especially  by  the  beginner,  before  being  replaced  under  the 
glass  case.  Stains  are  to  be  removed  from  the  brass  work  with 
a  linen  rag ;  dust  which  has  settled  on  the  mirror,  eye-piece,  etc., 
by  means  of  a  fine  camel's-hair  brush.  Although  these  proce- 
dures consume  some  time,  they  are  still  of  great  value  for  the 
protection  of  the  instrument  and  the  preservation  of  its  original 
power  of  performance,  especially  if  the  objectives  are  also 
examined  each  time  they  are  used. 

The  objectives  are  best  cleaned,  after  removing  the  dust  with 
a  camel's-hair  pencil,  by  means  of  a  piece  of  fine  linen  rendered 
soft  by  frequent  washing.  Fine  leather  or  elder  pith  may  also 
be  used.  Some  stains  are  to  be  removed  with  distilled  water  ; 
others,  as  glycerine  for  example,  require  a  cloth  freshly  moist- 
ened with  alcohol.  A  larger  quantity  of  alcohol  is  to  be  avoided, 
as  the  fluid  might  possibly  get  into  the  setting  of  the  lens  and 
reach  the  Canada  balsam  which  cements  the  crown  and  flint 
glasses  together. 


96  SECTION"    FIFTH. 

This  wetting  of  the  lenses  rarely  happens  to  the  more  expert. 
It  is  obvious,  that  where  reagents  are  being  used  it  is  to  be 
particularly  avoided,  and  the  greatest  caution  is  therefore  requi- 
site. The  objectives  used  should  be  as  weak  as  possible  with 
long  foci,  and,  when  much  of  this  kind  of  work  is  to  be  done, 
the  stage  is  to  be  covered  with  a  glass  plate,  which  latter  may 
be  fastened  with  clamps,  when  there  are  any  on.  the  stage. 
Broad  slides  for  the  specimens  also  afford  some  protection. 

Notwithstanding  every  precaution,  the  optical  portions  of  the 
instrument  require  cleaning,  after  a  time,  in  consequence  of  a 
fatty  coating  which  settles  on  the  objective  and  eye-piece,  and 
renders  the  image  quite  dim.  Instruments  which  have  been 
used  for  years  almost  always  show  this  coating.  One  should 
not  be  too  anxious  about  such  a  cleaning  process,  as  by  using  a 
good  brush  and  fine  linen  the  glasses  of  the  microscope  do  not 
suffer  in  the  least. 

The  microscopist's  work-table  should  be  large  and  massive,  so 
that  it  may  stand  sufficiently  firm.  A  hard-wood  board,  at  one 
or  both  sides  of  which  small  slabs  of  slate  may  be  inserted  for 
objects  which  require  preparatory  manipulation  to  rest  upon,  is 
most  to  be  recommended  as  a  table-top. 

A  series  of  drawers  is  a  valuable  addition  to  the  table.  A 
number  of  smaller  accessory  apparatuses  which  are  necessary  to 
the  microscopist  may  be  kept  in  these,  and  are  best  preserved 
in  this  way  from  dust  and  other  contaminating  influences. 
*  In  these  are  kept  the  slides,  the  various  sorts  of  glass  covers, 
glass  vessels,  drawing  arrangements,  accessory  apparatus  for  the 
microscope,  the  linen  rags  for  cleaning,  etc. 

A  few  bell-glasses  and  glass  cases  are  necessary  on  the  work- 
table  to  protect  things  which  have  been  temporarily  set  aside 
from  dust. 

Reagents  are  to  be  removed  from  the  table  after  being  used, 
and  kept  in  another  place. 

The  question  as  to  what  corporeal  and  psychical  qualities  the 
microscopist  should  possess,  is  discussed  with  great  profound- 
ness in  many  works.  We  think  that  it  may  be  here  omitted. 
Acute  mental  organs,  calmness,  love  of  truth  and  talent  for 
combination  are  qualities  which  the  physician  and  the  naturalist 


USE    OF   THE    MICROSCOPE.  97 

should  always  possess.  He  who  has  not  these,  whose  perceptive 
faculties  are  clouded  and  the  impartiality  of  whose  observations 
are  constantly  disturbed  by  a  lively,  excited  imagination,  should 
keep  away  from  the  microscope  as  well  as  from  the  profession 
of  medicine. 

For  microscopical  observation  and  work  it  is  necessary  to 
have  visual  organs  capable  of  moderate  endurance.  Somewhat 
short-sighted,  light  eyes  are  generally  the  best  adapted.  He 
who  is  so  fortunate  as  to  possess  two  equally  good  eyes,  should 
accustom  himself  to  employ  them  alternately.  Every  microsco- 
pist  who  uses  one  eye  for  a  long  time  continuously  in  looking 
into  the  microscope  while  the  other  eye,  though  remaining  open, 
is  unemployed,  knows  how  much  the  acuteness  of  the  one  has 
increased  while  the  passive  eye  has  acquired  a  certain  irritabil- 
ity, so  that  when  the  latter  is  used  in  order  to  relieve  the  other, 
the  field  of  vision  appears  much  brighter  and  weariness  soon 
makes  its  appearance.  Where  one  eye  is  evidently  weaker  than 
the  other,  the  microscopical  work  naturally  falls  to  the  latter. 
One  should  accustom  one's  self  from  the  beginning,  while  look- 
ing with  one  eye  into  the  instrument,  to  keep  the  other  open 
also.  The  attention  is  concentrated  so  predominantly  in  the 
active  organ  that  the  observer  is  no  longer  conscious  of  the  im- 
pressions made  on  that  which  is  unemployed. 

For  the  protection  of  the  visual  powers,  one  should  not  work 
too  continuously,  avoiding  the  earlier  morning  hours,  as  well  as 
the  time  immediately  after  dinner.  Leave  off  as  soon  as  fatigue 
commences.  For  beginners  especially,  whose  eyes  often  become 
rapidly  tired  from  the  unusual  nature  of  the  visual  act,  this  is 
advisable,  until  later  when  long  practice  has  accustomed  them 
to  more  continuous  labor. 

Whether  to  stand  or  sit  while  working,  is  to  be  determined 
by  one's  previous  habits.  Bending  the  head  down  over  verti- 
cal microscopes  usually  causes  but  little  inconvenience.  English 
microscopists,  however,  as  a  rule  lay  great  weight  on  the  oblique 
or  horizontal  position  of  the  tube  and  of  the  whole  instrument,  to 
prevent  the  neck  from  becoming  tired,  or  a  flow  of  blood  to 
the  head,  so  that  not  only  their  large,  but  also  quite  simple 
microscopes  have  such  an  arrangement.  But,  according  to  our 


98  SECTION   FIFTH. 

Continental  notions,  the  inconvenience  of  an  oblique  or  vertical 
position  of  the  stage  is  too  great,  when  more  than  the  examina- 
tion of  tests  is  concerned ;  this  arrangement  has  not,  therefore, 
become  very  generally  adopted. 

Very  important  for  the  protection  of  the  eyes  is  the  pre- 
viously mentioned  judicious  shading  of  the  field,  and  the  skilful 
application  of  the  diaphragm  (fig.  22,  page  25). 

The  gift  of  seeing  and  observing  with  the  microscope  is,  like 
all  human  abilities,  unequal,  greater  with  one  person,  less  with 
another  ;  but  with  a  little  perseverance  it  may  be  acquired  to 
a  sufficient  degree  by  most  persons. 

The  peculiar  nature  of  the  microscopic  images  causes  some 
difficulties  for  every  commencing  observer.  The  compound 
microscope  shows  us  only  that  stratum  of  the  object  which  lies 
directly  in  the  focus,  and  everything  else,  which  lies  in  other 
planes,  either  not  at  all  or  only  indistinctly.  At  the  same  time, 
in  the  usual  manner  of  examination,  the  whole  specimen  is 
transparent,  illuminated  from  beneath  and  not  from  above,  as 
in  ordinary  vision.  Things  which  lie  in  other  planes,  higher  or 
lower,  only  appear  after  altering  the  focus,  and  this  condition 
is  much  more  appreciable  with  strong  objectives  of  a  high 
angle  of  aperture  than  with  weaker  objectives  of  a  lower  angle 
of  aperture.  Hence  it  follows,  that  we  are  able  to  recognize 
immediately  the  outline  of  an  object,  and  the  relation  of  length 
and  breadth,  but  not  its  thickness  or  its  entire  form.  We  are 
able  to  obtain  these  only  by  a  combination  of  the  various  micro- 
scopic images  received  by  varying  the  focal  adjustment.  Here 
the  beginner  frequently  meets  with  considerable  difficulties, 
and  errors  may  arise  from  improperly  combining  the  images. 
In  this  kind  of  vision  we  are  deprived  of  the  aid  which  enables 
us,  in  ordinary  vision,  to  judge  rapidly  of  the  shape  of  the 
object.  The  form  of  a  microscopic  object,  regarded  with 
incident  light,  is,  for  this  reason,  generally  more  readily 
comprehended.  The  appreciation  of  the  form  of  a  blood- 
cell  is  not  difficult  for  those  who  are  somewhat  practised, 
but  the  contrary  is  the  case  in  ascertaining  the  polyangular 
shape  of  many  diatomacese,  or  the  form  of  a  cavity  in  an 
organic  part.  The  comparison  of  a  number  of  sections  made  in 


USE    OF   THE    MICROSCOPE.  99 

horizontal,  vertical,  and  oblique  directions,  a  means  resorted  to 
by  botanists  especially,  is  here,  when  practicable,  of  great  value. 

The  estimation  of  the  form  is  difficult  in  still  another  man- 
ner, namely,  in  consequence  of  the  extraordinary  diminutiveness 
of  an  object.  With  a  little  practice  it  is  not  difficult  to  recog- 
nize the  relations  of  relief  in  a  microscopic  object,  for  example, 
to  distinguish  a  somewhat  larger  concave  surface  from  a  convex 
one,  if  only  by  means  of  a  combination  of  various  images. 
When  such  surfaces  are  extremely  small,  as  is  the  case,  for 
example,  with  the  delicate  areolations  of  the  so  frequently  em- 
ployed test  object,  the  Pleurosigma  angulatum,  the  discrimina- 
tion is  very  difficult.  Thus,  as  has  been  previously  remarked, 
these  last-mentioned  areolae  have  been  declared  by  some 
excellent  observers  to  be  convex,  by  others  to  be  excavated,  and 
the  matter  has  not  yet  been  definitely  decided. 

Welcker  has  given  us  a  good  means  for  discriminating  be- 
tween convex  and  concave  bodies.  The  former  act  as  convex 
lenses,  the  latter  as  concave.  When  we  start  with  the  tube  in 
a  medium  position,  a  convex  body  will  appear  lighter  by  raising 
the  microscope  tube,  a  concave  by  lowering  the  tube  ;  a  globular 
structure  and  a  hollow  sphere,  a  ridge  and  a  furrow,  may  thus 
be  discriminated. 

It  is  much  easier  to  recognize  the  shape  of  microscopic  ob- 
jects by  means  of  weaker  objectives  than  by  the  employment 
of  very  strong  combinations  with  large  angles  •  of  aperture,  so 
that  herein  also  lies  a  weighty  argument  in  favor  of  the  former. 
Although  the  practised  microscopist  may  accomplish  his  pur- 
pose with  very  strong  objectives,  still  it  is  frequently  desirable 
to  have  a  well-constructed  medium  power,  with  the  smaller 
angle  of  former  days,  added  to  one's  instrument.  The  English 
opticians  have  sought  relief  in  this  direction  by  adding  a  dia- 
phragm to  the  lenses  with  large  angles  of  aperture. 

One  soon  learns  to  appreciate  the  foreign  substances  which 
contaminate  the  microscopic  image,  much  of  which  may  be 
avoided  by  neatness  and  carefulness  in  making  the  preparation. 
One  should  make  one's  self  familiar,  and  as  soon  as  possible, 
with  the  appearance  of  air  bubbles,  oil  globules,  starch  granules, 
fibres  of  linen  and  cotton,  etc. 


100  SECTION   FIFTH. 

It  is  also  important  to  compare  the  image  which  an  object 
presents  by  transmitted  light  with  that  which  it  affords  by  inci- 
dent light.  Among  other  things,  the  appearance  of  one  and  the 
same  object  in  media  of  various  refracting  powers  is  also  to  be 
studied. 

The  optical  portion  of  microscopic  work  is  much  more  diffi- 
cult to  acquire  than  the  manual,  such  as  the  cautious  use  of  the 
adjusting  screws  and  the  mirror,  and  the  steady  and  net  jerking 
movement  of  the  object  through  the  field.  In  this  place  the 
important  principle  should  be  impressed,  that  movements  which 
can  be  securely  accomplished  by  the  human  hand  are  to  be  left 
to  it,  and  are  not  to  be  executed  by  screws  and  other  mechanical 
contrivances.  Every  experienced  microscopist  will  regard  the 
massive  accessory  apparatus  of  the  large  English  microscopes 
as  being  somewhat  superfluous  and  inconvenient. 

The  inversion  of  the  image  by  the  compound  microscope 
causes  some  difficulty  for  the  beginner.  One  soon  becomes 
accustomed  to  this,  however,  and  finally  to  such  a  degree  that 
it  is  no  longer  noticed,  and  one  is  only  reminded  of  it  when 
using  an  erector  (where  the  inverted  image  is  again  inverted  by 
means  of  a  lens  placed  within  the  tube  of  the  microscope,  or  by 
a  prism  on  the  eye-piece).  As  this  inversion  is  attended  with 
optical  disadvantages,  such  instruments  have  not  been  exten- 
sively adopted,  and  are  only  convenient  for  microscopic  dissec- 
tions when  furnished  with  weak  lenses. 

Finally,  one  word  more  is  necessary  concerning  the  phenomena 
of  movement  visible  under  the  microscope.  Not  everything 
which  is  here  seen  in  motion  is,  for  that  reason,  to  be  pro- 
nounced vital. 

Currents  sometimes  occur  in  water,  with  which  one  should 
become  familiar  in  order  to  guard  against  error  in  other  cases. 
For  instance,  if  alcohol  is  mixed  with  water,  the  small  bodies 
suspended  in  it  acquire  a  rapid  motion,  which  continues  until 
both  fluids  are  equalized,  that  is,  have  become  thoroughly 
blended. 

Then  very  small  particles  of  substances  which  are  insoluble 
in  water  present  an  uninterrupted  dancing  motion,  the  cause  of 
which  is  still  unexplained,  but  is,  at  all  events,  a  purely  physical 


USE    OF   THE    MICROSCOPE.  101 

phenomenon.  This  movement  is  called  the  "  Brunoniau  mole- 
cular motion." 

Finely  powdered  charcoal,  small  crystals,  the  grannies  of  a 
coloring  material  exhibit  the  same  peculiar  dancing  movement 
as  the  molecules  of  fat  and  melanine  taken  from  the  animal 
body.  In  certain  cases  we  can  observe  the  same  motion  in  the 
fluid  contents  of  cells  as  are  taking  place  in  the  surrounding 
fluids. 

On  the  vertebral  column  of  the  frog,  at  the  points  of  exit  of 
the  spinal  nerves,  lie  small  white  collections  of  columnar- 
shaped  crystals  of  the  carbonate  of  lime.  These,  deposited  in  a 
drop  of  water,  present  one  of  the  finest  examples  for  the  study 
of  the  molecular  movement.  Larger  crystals,  of  about  -j-^  to 
•yfa'",  lie  perfectly  quiet,  so  long  as  there  is  no  current  in  the 
fluid.  Those  of  half  this  size  are  seldom  found  to  have  the 
dancing  motion.  The  smaller  the  columns  are,  the  more  gen- 
erally the  movement  is  to  be  met  with,  and  the  smallest,  of 
ToW"  and  smaller,  on  which  we  are  no  longer  able  to  recognize 
the  columnar  form,  are  engaged  in  a  continual,  restless  motion. 

The  examination  of  the  molecular  movement  is  instructive 
for  the  beginner  in  still  another  regard.  One  readily  forgets 
how  much  the  excursions  of  a  moving  object  are  enlarged  by 
the  optical  apparatus  of  the  microscope.  The  dancing  of  a 
small  molecule  will  appear  slight  to  the  eye  with  200-fold  en- 
largement, but  very  energetic,  011  the  contrary,  with  an  enlarge- 
ment of  1000-1500  diameters. 

This  is  repeated  in  the  vital  movements  which  are  seen  with 
the  instrument.  An  animalcule  which  we  examine  with  very 
strong  lenses  shoots  quickly  through  the  field,  while  with  the 
lowest  powers  it  does  not  swim  with  any  considerable  degree  of 
rapidity  through  the  water.  When  the  circulation  in  the  web 
of  the  frog's  foot  or  in  the  tail  of  its  larva  is  examined  with 
high  powers,  the  blood-corpuscles  hasten  through  the  capillary 
passages,  while  in  reality  the  current  in  the  capillary  vessels  is 
quite  slow. 

There  is  still  another  consideration  which  is  not  to  be  disre- 
garded in  observing  the  phenomenon  of  microscopic  motion. 
"Wlieii  a  series  of  movements  follow  each  other  with  great 


102  SECTION   FIFTH. 

rapidity,  we  may  readily  recognize  the  total  movement,  but  not 
the  single  motions ;  these  are  separately  appreciable  to  the  eye 
only  when  the  entire  phenomenon  is  regarded.  We  shall  be- 
come acquainted  with  an  example  of  this,  the  ciliary  movement, 
in  a  later  section. 

Finally,  we  have  to  mention  still  another  series  of  movement 
phenomena  which  has  recently  attracted  the  attention  of  investi- 
gators more  and  more, — we  refer  to  the  changes  in  shape  of  the 
living  animal  cell. 

Isolated  examples  of  this  marvellous  change  of  shape,  especi- 
ally in  the  bodies  of  the  lower  animals,  were  known  long  ago. 
At  present  it  is  known  that  the  young  animal  cell,  so  long  as 
the  cell  body  still  consists  of  the  original  substance,  the  so-called 
protoplasma,  is  endowed  in  the  highest  organisms  also  with  a 
capacity  for  independent  vital  contraction.  Numerous  cells  of 
the  normal  superstructure,  likewise  pathological  new  formations 
— so  long  as  they  possess  the  character  of  youthfulness — 
present  the  changes  mentioned.  Such  cells  have  been  seen  to 
pass  out  (after  the  manner  of  the  amoebae)  through  the  walls  of 
the  capillaries  (A.  Waller,  Colmheim),  to  wander  through  the 
lining  tissue,  and  to  take  up  into  their  contractile  cell-like 
bodies  small  particles,  such  as  molecules  of  indigo,  anilin,  cin- 
nabar, and  carmine,  the  finest  milk  globules,  and  even  extrava- 
sated  colored  blood-corpuscles ;  so  that  the  view  here  opens  into 
a  new  world  of  minute  actions,  and  it  has  already  furnished 
extremely  important  information,  to  which  we  shall  again  refer. 

If  in  any  microscopic  investigations  the  most  conservative 
preparation  is  requisite,  it  is  just  here. 

In  order  not  to  kill  the  cell  prematurely,  one  must  employ 
a  truly  indifferent  fluid  medium.  Whoever  proceeds  to  make 
such  investigations  with  the  old  idea  of  possessing  such  indiffer- 
ent fluids  in  solutions  of  sugar  and  salt,  albumen  and  water,  or 
humor  vitreus,  will  soon  become  convinced  of  the  contrary.  In 
general  only  those  fluids  which  surround  the  cell  in  the  body 
can  be  called  truly  indifferent.  In  many  cases  the  indication 
may  be  fulfilled  with  iodine-serum  (see  below),  or  a  similar  com- 
position. The  greatest  caution  is  necessary  to  prevent  pressure 
and  evaporation.  The  very  thin  covering  glass  is  to  be  support- 


USE    OF    THE    MICROSCOPE. 


103 


ed  by  placing  beneath  it  the  fragments  of  one  of  its  predeces- 
sors, which  are  usually  not  very  rare  with  the  mieroscopist,  or 
— what  is  for  many  cases  still  better — the  covering  glass  is  en- 
tirely omitted. 

Recklinghausen  has  invented  a  very  efficient  little  apparatus 
for  preventing  the  evaporation 
of  the  fluids.  This,  the  "  moist 
chamber,"  the  reader  will 
readily  comprehend  by  glanc- 
ing at  fig.  63.  The  object  is 
placed  011  the  somewhat  broad 
ground  slide  (d)  in  the  usual 
manner.  The  glass  ring  (&), 
with  its  under  surface  likewise 
ground  off,  rests  on  the  slide  at  some  distance  from  the  object. 
This  ring  may,  in  certain  cases,  be  made  higher.  A  tube  (b)  of 
thin  rubber  is  fastened  as  firmly  as  possible  about  the  ring. 
The  upper  end  (c)  of  the  tube  is  fastened  round  the  neck  or 
tube  of  the  microscope  with  a  small  rubber  band.  In  order  to 
keep  the  space  thus  enclosed  saturated  with  moisture,  two  strips 
of  elder  pith  or  bibulous  paper,  saturated  with  fluid,  are  to  be 
placed  at  the  inner  surface  of  the  glass  ring,  and  the  external 
surface  of  the  lower  border  of  the  ring  is  to  be  surrounded  with 
several  little  pads  of  moist  blotting  paper. 

A  moist  chamber  may  be  made  in  still  another,  more  simpli- 
fied manner  (fig.  64).     A  glass  ring  (£),  a  few  millimetres  in 


Pig.  63.     Eecklinghausen's  moist  chamber. 


Fig.  64.    A  more  simplified  moist  chamber. 


height,  is  to  be  cemented  on  to  an  object  slide  (a).     A  few  drops 
of  water  are  to  be  cautiously  placed  at  the  inner  edge  of  the 


104 


SECTION    FIFTH. 


former  with  a  brush.  The  object  is  to  be  placed  on  a  circular 
covering  glass  (c)  and  the  latter  then  turned  over  and  placed  on 
the  ring ;  in  this  way  all  pressure  is  necessarily  avoided. 

One  may  thus — with  the  aid  of  an  immersion  objective — fol- 
low the  movement  of  these  cells  for  hours,  and  even  days. 

The  last-mentioned  simple  apparatus  may  be  readily  convert- 
ed into  a  gas-chamber  (fig.  65).  The  thick  glass  plate  shows  a 


Fig.  65.    Strieker's  gas-chamber. 

ring  ground  out  at  the  bottom  of  the  chamber.  Two  glass  tubes 
are  cemented  into  the  two  half  canals.  One  of  these  tubes  (a\ 
connected  with  the  caoutchouc  tube  a?  serves  for  the  entrance 
of  the  gas,  the  other  (a1)  for  its  exit.  The  covering  glass  may 
be  more  securely  adapted  to  the  glass  ring  with  a  cement. 

Although  we  can  in  this  manner,  at  the  ordinary  temperature 
of  the  room,  study  the  cell  life  of  a  cold-blooded  vertebrate  ani- 
mal, for  example,  in  the  connective  tissue,  cornea,  blood,  and 
lymph  of  a  frog,  we  cannot,  with  the  same  success,  study  those 
from  the  body  of  a  warm-blooded  animal.  The  movement  is 
too  rapidly  retarded  by  the  surrounding  coldness.  A  condition 
as  to  temperature  resembling  that  of  the  living  organism  must 
be  attained  for  the  success  of  the  observation.  The  older  mi- 
croscopists  helped  themselves  in  this  dilemma,  so  far  as  it  was 
possible  to  do  so,  by  using  warmed  slides.  Be  ale  afterwards 
constructed  a  warmable  stage,  but  of  rather  crude  form.  Quite 
recently  a  celebrated  investigator,  M.  Schnltze,  has  rendered  a 
great  service  by  producing  an  apparatus  of  this  kind  which  ful- 
fils the  indications  more  completely. 


USE    OF   THE    MICROSCOPE. 


105 


Schultze's  apparatus  *  is  represented  by  our  fig.  66.  A  brass 
plate  A,  which  is  notched  (c)  posteriorly,  so  as  to  fit  on  to  the  sup- 
port of  the  microscope,  is  to  be  fastened  on  to  the  microscope 
stage  with  clamps.  It  is  perforated  at  a  for  the  illumination, 
and  at  its  front  part,  in  the  middle,  the  thermometer  (d)  is  placed 
slantingly ;  at  the  corners  are  the  two  arms  b.  Two  small  spirit 
lamps  under  the  latter  supply  the  heat.  The  lower  extremity 
of  the  thermometer  is  enclosed  in  the  brass  case  ~Ba,  which  has 


Fig.  66.     Schultze's  warmable  stage. 

two  somewhat  thicker  wooden  ledges  at  its  sides.  The  thermo- 
meter winds  round  the  aperture  in  the  stage,  passes  uncovered 
and  horizontally,  for  a  short  distance,  on  its  under  surface,  and 
then  bends  to  pass  through  the  opening  b  to  arrive  at  the  face  of 
the  graduated  metal  plate.  It  has  been  ascertained  by  experi- 
ment that  the  actual  temperature  of  the  object  is  indicated  by 
the  thermometer. 

It  is  scarcely  necessary  to  remark,  that  it  is  most  advantageous 
to  use  immersion  lenses  and  the.  moist  chamber  with  the  hot 
stage. 

Unfortunately,  this  apparatus  has  an  unpleasant  defect,  as 
Engelmann  has  shown.  The  temperature  of  the  object  is  occa- 

*  It  may  be  obtained  of  the  mechanician  Giessler,  in  Bonn,  for  nine  thalers, 
Prussian. 


106 


SECTION    FIFTH. 


sionally  reduced  very  considerably  by  the  metallic  setting  of  the 
lens  and  the  microscope  tube,  so  that,  in  this  case,  the  focal 
distance  of  the  objective  exerts  a  marked  influence.  The  inser- 
tion of  a  bad  conductor  of  heat  between  the  lens  and  the  micro- 
scope tube  has  been  proposed.  An  ivory  tube,  30  mm.  in  height, 
applied  in  this  manner,  lessens  this  defect  very  materially. 

Various  arrangements  have  been  contrived  for  the  purpose  of 
conducting  electrical  currents  through  an  object  under  the 
microscope.  We  introduce,  as  an  example,  the  simple  one  of 
Harting  (fig.  67). 


Fig.  67.    Hurting  s  electrical  apparatus. 

Two  somewhat  narrow  strips  of  tin-foil  AB  are  fastened  with 
starch  paste  on  to  a  glass  slide  abed;  a  portion  of  the  tin-foi1 
projects  beyond  the  ends  of  the  slide,  so  as  to  connect  with  the 
conducting  wires  of  the  galvanic  apparatus.  The  central  portion 
of  the  slide  remains  free.  The  two  glass  plates  defg  and 
h  i  k  I  are  to  be  ceni3ii'ed  over  these  strips  of  tin-foil  with 
marine  glue  or  a  mixture  of  pitch  and  rosin,  for  the  stage  clamps 
to  rest  on.  The  two  polar  wires  p  and  p  (for  which  platinum 
is  the  best  material)  are  not  fastened ;  they  receive  the  curve 
shown  in  the  figure  at  C.  The  part  m  r  s  rests  011  the  tin-foil, 
the  other  curved  portion  m  t  v  (to  which  may  be  given  any  curve 
desired)  dips  its  point  into  the  examining  fluid,  which  in  our 
drawing  is  surrounded  by  a  cell  D.  liarting's  apparatus  may 
ba  readily  modified. 


THE  PREPARATION  OF  MICROSCOPIC  OBJECTS. 

WITH  the  exception  of  the  finished  preparations  of  a  collec- 
tion, in  most  cases  the  objects  to  be  examined  require  prepara- 
tion, which,  as  we  have  already  remarked,  should  be  as  careful 
and  cleanly  as  possible.  It  is  only  when  the  blood,  mucus, 
pathological  fluids,  etc.,  are  examined,  that  the  mere  spreading 
out  of  a  drop  of  the  same  is  sufficient. 

The  object  slides,  which  are  simply  strips  of  glass,  serve  for 
the  reception  of  the  object  to  be  examined.  Several  dozen  of 
them  should  be  kept  on  hand  in  a  clean  condition,  protected 
from  dust  in  an  accurately  closing  box.  Good  slides  should  be 
made  of  pure  glass,  preferably  without  any  color,  and  the  edges 
should  be  ground,  for  the  protection  of  the  instrument.  Too 
great  thickness  of  the  glass  renders  the  use  of  the  stronger  objec- 
tives and  the  cylindrical  diaphragms,  which  then  become  neces- 
sary, inconvenient.  Therefore,  the  thickness  of  the  slides  should 
not  exceed  £— \'" .  The  most  convenient  form  is  that  of  a  long 
square  (3  inches  by  1  inch),  but  when  the  stage  is  narrow  they 
should  be  of  a  corresponding  width.  Square  slides  are  less 
suitable.  One  should  also  accustom  one's  self  to  place  the  object 
to  be  examined  in  the  centre  of  the  slide.  It  is  rarely  examined 
in  the  dry  condition,  but,  as  a  rule,  with  the  addition  of  some 
fluid ;  as,  \vater,  glycerine,  etc.  This  is  to  be  added  at  the  com- 
mencement of  the  preparation.  One  soon  learns  to  judge  of  the 
quantity  which  is  necessary. 

The  object  to  be  examined,  if  it  is  large,  and  especially  if  it  is 
thick, — as  for  example,  when  one  desires  to  examine  a  small 
embryo  or  an  injected  specimen  of  considerable  size,— is  to  be 
placed  with  some  fluid  in  a  watch-glass  under  the  microscope. 


108 


SECTION    SIXTU. 


Fig.  68.    Glass  box. 


Small  quadratic  glass  boxes,  about  an  inch  or  an  incli  and  a  half 
in  size  and  two  or  three  lines  in  depth,  are  more  convenient  for 

this    purpose.      Glass   cells,   as 

made  by  the  English  (see  further 
on,  at  the  preparation  of  micro- 
scopic objects),  may  also  be  em- 
ployed with  advantage.  Thick 
slides  with  an  excavation  in  the 
centre  are  less  suitable. 

The  preparation  is  seldom 
examined  uncovered ;  such  a 
method  of  examination  is  con- 
fined almost  entirely  to  the  cases  last  mentioned.  The  cover- 
ing glasses  or  covering  scales,  which  have  been  so  frequently 
alluded  to,  serve  for  a  covering.  Pieces  of  pretty  thick  glass 
were  formerly  used  with  low  powers ;  at  present  these  have 
gone  out  of  use,  since  thin  and  even  very  thin  glass  may  be  ob- 
tained from  England  at  slight  cost. 

As  we  have  seen  in  an  earlier  section,  the  thickness  of 
the  covering  glass  exerts  considerable  influence  on  the  opti- 
cal performance  of  the  stronger  objectives.  It  is  well, 
therefore,  to  have  these  glasses  arranged  in  a  series  of  various 
thicknesses,  which  are  kept  in  separately  designated  boxes. 
It  is  necessary  to  have  them  from  -5— J-'",  to  those  of  yV~iV" 
in  thickness,  according  to  the  objectives  with  which  they  are  to 
be  used.  Even  the  pressure  of  this  thin  glass  is  occasionally 
too  great  for  very  delicate  objects,  if  one  desires  to  avoid 
crushing  or  splitting  them.  In.  such  cases  it  is  necessary  to 
insert  a  harder  substance  between  the  slide  and  the  cover,  a 
precautionary  measure  which  has  already  been  alluded  to  on 
a  preceding  page.  Thicker  covers  may  be  cut  from  thin 
plate  glass. 

A  few  special  instruments  are  requisite  for  making  prepara- 
tions. But  one  should  not  think  that  they  are  indispensable. 
In  practised  hands  the  same  and  even  more  may  be  accom- 
plished, in  a  shorter  time,  writh  simple  tools  than  with  compli- 
cated ones.  A  number  of  microscopic  knives,  small  forceps, 
and  scissors  have  been  invented,  it  is  true,  but  they  are  gener- 


THE    PREPARATION    OF    MICROSCOPIC    OBJECTS.       109 

ally  used  by  their  inventors  only,  and  are,  as  a  rule,  quite 
worthless  trash. 

First  of  all,  one  should  have  several  fine  forceps  terminating  in 
thin  points  for  seizing  objects.  Such  should  be  selected  as  have 
light  springs,  and  not  the  stiff  ones  which  many  anatomists  are 
accustomed  to  use.  The  points  should  be  either  quite  smooth 
or  only  slightly  grooved.  A  hooked  point  is  unsuitable.  Many 
objects,  especially  those  of  a  delicate  nature,  are  more  conve- 
niently moved  with  a  camePs-hair  brush. 

The  scissors  are  most  frequently  used  for  dissecting.  A  fine 
pair  of  so-called  eye  scissors  is  indispensable.  A  small  pair 
with  curved  blades  is  very  convenient  for  many  purposes ; 
here  and  there,  a  pair  of  fine  elbow  scissors  also  renders  good 
service. 

A  few  small  knives,  though  useful,  are  of  relatively  inferior 
value.  Several  very  fine  scalpels  with  narrow-pointed  blades, 
when  possible,  of  somewhat  strongly  hardened  steel,  are  more 
serviceable.  The  ordinary  anatomical  scalpels  are  much  too 
clumsy,  and,  as  a  rule,  are  made  from  too  soft  steel  to  be  useful 
for  the  microscopist. 

When  a  still  finer  cutting  instrument  is  necessary,  the  ordi- 
nary cataract  needle  is  to  be  used.  It  is  also  extremely  useful 
for  moving  small  objects. 

The  tearing  of  microscopic  objects  is  frequently  necessary  in 
histological  investigations.  This  may  be  accomplished  with 
very  finely  pointed  steel  needles,  of  medium  length,  let  into 
wooden  handles.  When  this  picking  process  is  necessary  it 
should,  in  consequence  of  the  minuteness  of  the  elements  of 
the  human  body,  always  be  performed  with  accuracy  ;  devoting 
the  few  minutes  required,  as  one  will  be  rewarded  for  the  little 
pains,  by  a  good  preparation.  Beginners  very  frequently  fail 
in  this.  They  stop  picking  too  soon  on  a  preparation  which 
was  too  large  at  the  commencement. 

Not  unf  requently,  in  such  cases,  the  work  is  so  fine  that  one 
must  have  recourse  to  magnifying  glasses,  to  the  loup  or  the 
simple  microscope.  A  very  great  inconvenience  is  connected 
with  the  latter  when  used  with  stronger  lenses ;  the  shortness  of 
the  focus  soon  renders  needle-work  impossible.  Zeiss  deserves 


110 


SECTION    SIXTH. 


credit,  therefore,  for  having  produced  the  useful  microscope 
icpresented  in  fig.  69.  It  has,  on  a  short  tube,  an  objective 
consisting  of  three  lenses,  and  has  a  concave  lens  as  an  eye- 
piece. It  permits  the  use  of  needles,  even  with  150-200  fold 
enlargement. 


Fig.  69.    Zeiss'  new  dissecting  microscope. 

[A  very  economical  and  efficient  substitute  for  the  simple 
microscope  has  been  devised  by  Dr.  Curtis.  It  consists  simply 
of  a  binocular  ophthalmoscope,  the  mirror  of  which  is  replaced 
by  a  biconvex  lens  of  one  or  two  inches  focus.  The  whole  rests 
over  a  small  aperture  in  a  little  wooden  box,  the  front  and  part 
of  the  sides  of  which  are  removed  for  convenience  of  manipu- 
lation with  the  preparation  which  is  placed  on  a  support  in  the 
box.  As  will  be  readily  appreciated,  this  gives  an  upright, 
stereoscopic  image,  and  a  considerable  magnifying  power.] 

It  is  often  found  necessary  to  make  very  thin  sections  from 


THE    PREPARATION    OF   MICROSCOPIC    OBJECTS.       Ill 

fresh,  and  especially  from  artificially  hardened  tissues.  Knives 
with  double  blades  running  parallel,  and  close  to  each  other, 
have  been  used  for  this  purpose.  The  double  knife  invented 
by  Professor  Valentin  has  become  the  best  known.  It  is  not 


Fig.  70.    Double  knives.    1  that  of  Valentin ;  2  the  improved  English  instrument. 

easy  to  produce  a  good  instrument,  such  as  is  represented  by 
our  fig.  YO  at  1,  and  when  not  well  made  it  is  entirely  unservice- 
able. This  instrument  has  received  a  judicious  improvement 
in  the  hands  of  English  cutlers.  We  see  such  an  improved 
form  of  the  double  knife  represented  in  the  same  cut,  at  fig.  2. 
It  is  much  more  desirable  to  make  thin  sections,  with  the 
free  hand,  by  means  of  a  good  razor.  Any  one  who  has  such 
an  one  at  his  command,  and  has  acquired  the  necessary  dex- 
terity, will  discard  the  double  knife.  Good  English  razors,  of 
light  construction,  with  small  blades,  are  the  most  suitable. 
For  many  purposes,  it  is  well  to  have  them  ground  flat ;  but  it 
is  preferable  to  have  the  blade  ground  hollow  for  very  thin  and 
fine  sections.  To  preserve  it  in  a  proper  condition,  it  is  neces- 
sary that  it  should  be  well  sharpened,  and  the  strap  should  be 
frequently  used.  The  blade,  as  well  as  the  preparation  to  be 
cut,  must  be  well  moistened,  for  when  they  are  dry  a  good  sec- 
tion can  never  be  made.  The  fine  section  is  best  removed  from 
the  wet  blade  by  means  of  a  brush ;  it  is  then  to  be  carefully 
and  cautiously  spread  out  on  the  slide.  For  making  very  large 
sections  with  sufficient  delicacy,  howrever,  the  razor  is  unservice- 
able, in  consequence  of  the  thickness  of  the  back  of  its  blade. 
In  such  cases,  according  to  Thiersch,  another  instrument  may 
be  advantageously  employed ;  it  consists  of  a  knife-blade  of  the 
thickness  of  paper  (about  1  crn.  in  breadth  by  20  cm.  in 


112 


SECTION    SIXTH. 


lengt1 ),  which  is  to  be  stretched  in  a  watchmaker's  ordinary 
saw-bow. 

[The  best  razors  which  I  have  seen  for  anatomical  work  are 
those  made  by  Le  Coultre,  in  Switzerland.  The  blades  are  as 
thin  as  paper,  and  are  made  of  good  material.  The  price  varies 
according  to  the  width  and  number  of  the  blades.  Those  with 

o 

one  wide  blade  cost  $1.75,  gold ;  with  two  wide  blades,  $2.50. 
They  may  be  purchased  of  the  agents,  Taylor,  Olmstead  & 
Taylor,  No.  5  Bond  St.,  K  Y.] 

Henson  has  also  invented  an  apparatus,  the  "  section  cutter," 
to  be  used  under  the  microscope,  for  making  very  fine  sections. 
I  have  no  personal  experience  in  its  use,  and  quite  as  little  of 
an  instrument  recently  made  by  His,  of  Basel,  and  recommended 
by  others.  Such  apparatuses  are  certainly  convenient  in  certain 
cases ;  as  a  rule,  the  same  end  may  be  accomplished  by  a  prac- 
tised hand. 

[A  very  efficient  "  section  cutter  "  has  been  contrived  by  Dr. 


FIG  I 


Pig.  70*.    Curtis'  "section  cutter." 


Edward  Curtis,  of  this  city,  to  whom  I  am  indebted  for  the 
accompanying  wood-cut. 

The  following  description  of  the  apparatus,  and  the  manner 
of  using  it,  is  condensed  from  an  article  presented  by  Dr.  C.  at 


THE    PREPARATION    OF   MICROSCOPIC    OBJECTS.         113 

the  annual  meeting  of  the  American  Ophthalmological  Society, 
held  at  Newport,  July,  1871. 

The  apparatus  is  shown  in  fig.  70*.  "  It  consists  of  the  part 
A  (fig.  I.),  for  holding  the  object  to  be  cut,  modelled  after  a 
form  of  section  cutter  in  common  use ;  and  of  the  cutting  part 
B,  after  my  own  device,  composed  of  a  long  straight  knife  held 
in  a  frame.  The  holder,  A,  consists  of  a  heavy  brass  plate, 
faced  with  glass,  six  inches  long  by  three  and  three-quarters 
wide,  from  the  centre  of  which  is  sunk  a  hollow  cylindrical 
barrel,  one  inch  and  three-quarters  in  depth,  and  one  inch  and 
one-quarter  in  diameter,  inside  measurement.  Through  the 
bottom  piece  of  this  barrel  (which  unscrews  for  convenience) 
works  a  screw  shaft,  furnished  with  a  large  milled  head.  The 
threads  of  the  screw  are  fifty  to  the  inch,  and  the  circumference 
of  the  milled  head  is  marked  off  into  eighths,  so  that,  if  desired, 
the  thickness  of  the  sections  cut  can  be  measured.  Attached  to 
the  under  surface  of  the  face  plate,  near  one  end,  is  a  screw 
clamp  for  fastening  the  apparatus  to  the  edge  of  a  table,  so  as 
to  leave  both  hands  of  the  operator  at  liberty  to  work  the  cutter. 

"  The  principle  of  this  (  holder,'  as  it  might  be  called,  is  very 
simple.  The  object  to  be  cut  is  first  embedded  in  a  cast  of  wax 
and  oil,  or  paraftine,  made  to  exactly  fit  the  bore  of  the  barrel ; 
this  mass  is  then  pressed  into  the  barrel,  pushed  upward  by 
turning  the  milled  head  of  the  screw-shaft  until  it  projects 
slightly  above  the  level  of  the  face-plate,  when  the  projecting 
part  is  cut  off  by  a  sweep  of  the  knife.  Another  turn,  or  a 
fraction  of  a  turn,  of  the  milled  head  is  then  made,  and  again 
the  projecting  portion  is  cut  off,  this  time  as  a  smooth,  even  sec- 
tion of  microscopic  thinness.  For  a  cutter  I  had  a  straight 
knife  made,  with  a  blade  eight  inches  long,  one  and  a  quarter 
inch  wide,  and  three-twentieths  of  an  inch  thick  at  the  back, 
and  with  the  sides  concave  like  a  razor.  This  I  at  first  used  by 
itself,  sweeping  it  over  the  surface  of  the  holder  in  cutting  the 
sections,  but  I  found  that,  from  the  length  and  thinness  of  the 
blade,  it  was  apt  to  bend  under  pressure,  and  so  fail  to  cut  an 
even  section,  and  also  that  the  edge  soon  got  dull  from  friction 
upon  the  face-plate.  To  obviate  these  difficulties,  I  conceived 
the  idea  of  having  the  knife  fixed  in  a  frame  which  should 


114  SECTION    SIXTH. 

answw  uie  uouble  purpose  of  holding  the  blade  stiff,  and  carry- 
ing it  with  the  edge  raised  slightly  above  the  level  of  the  sur- 
face of  the  holder,  so  that  the  under  surface  of  the  arms  of  the 
frame  should  be  the  bearing  surface  upon  the  holder,  and  the 
edge  of  the  knife  be  allowed  to  touch  nothing  but  the  tissue  to 
be  cut.  The  design  of  the  frame  will  be  seen  at  once  from  the 

o 

figure  ;  it  is  made  of  brass,  and  the  knife  is  pushed  into  place 
from  behind,  under  a  couple  of  springs,  which  hold  the  blade 
down,  and,  when  pressed  home,  the  knife  is  kept  from  slipping 
back  by  a  little  fastening,  which  is  pushed  against  the  back  of 
the  blade  and  then  fixed  by  a  turn  of  a  quick  screw.  Besides 
the  advantages  of  the  frame  in  holding  the  knife  stiff,  and  keep- 
ing its  edges  from  scraping  over  the  surface  of  the  holder,  its 
weight  and  broad  tread  make  it  sweep  much  more  steady  and 
true  than  that  of  a  light  knife  used  by  itself." 

This  apparatus  is  so  efficient  that  Dr.  C.  has  often  cut  with  it 
sections  of  an  entire  human  eye,  thin  enough  for  microscopical 
examination. 

In  preparing  the  tissue  and  cutting  the  sections,  however, 
there  are  one  or  two  points  which  it  is  necessary  to  observe  in 
order  to  get  the  best  results.  The  tissues  are  to  be  hardened  in 
the  usual  manner,  with  bichromate  of  potash  and  alcohol. 
When  the  consistence  is  suitable  for  cutting,  the  piece  is  to  be 
transferred  to  oil  of  cloves,  where  it  is  allowed  to  stay  until 
thoroughly  impregnated  with  the  oil ;  this  takes  from  half  an 
hour  to  several  hours,  according  to  the  size  and  solidity  of  the 
specimen.  The  piece  is  now  to  be  embedded  for  cutting. 

"In  order  to  get  a  mould  for  the  paraffine  which  shall  yield 
a  cast  of  the  right  size  to  go  into  the  barrel  of  the  section-cut- 
ter, a  solid  brass  plug  (fig.  IY.  of  the  woodcut),  one  inch  high, 
and  made  to  exactly  fit  the  bore  of  the  barrel,  forms  part  of  the 
apparatus.  In  one  end  of  it  an  oval  excavation  is  countersunk, 
to  let  the  cast  of  paraffine  take  a  firm  hold  of  its  surface,  and 
to  keep  the  same  from  turning  round  under  the  pressure  of  the 
knife.  A  strip  of  letter-paper,  about  two  inches  and  a  half 
wide,  is  now  wrapped  tightly  around  this  plug,  the  plug  being 
in  the  middle  of  the  strip,  so  that  the  paper  projects  at  both 
ends.  The  part  projecting  beyond  the  fiat  end  of  the  plug  is 


THE    PEEPARATIOX    OF   MICROSCOPIC    OBJECTS.        115 

folded  down  over  it,  and  the  opposite  projecting  cylinder  of 
paper  then  forms  a  cup,  with  the  excavated  face  of  the  phig 
for  a  bottom,  of  the  exact  calibre  of  the  barrel  of  the  section- 
cutter.  Into  this  the  melted  paraffine  is  to  be  poured.  A  cap- 
sule containing  paraffine,  or  wax  and  oil,  in  considerable  excess 
of  the  amount  required  for  the  embedding,  is  held  over  a  lamp 
till  the  mass  is  just  melted,  when  it  is  taken  off  and  the  piece  of 
tissue  dropped  into  it  and  stirred  about  for  a  few  minutes  to 
rinse  off  the  excess  of  oil  of  cloves.  Then  some  of  the  melted 
material  is  poured  into  the  paper  mould,  the  piece  of  tissue 
immediately  transferred  to  the  same,  arranged  in  proper  posi- 
tion, and  the  whole  set  aside  to  cool.  When  perfectly  cold  and 
hard,  the  paper  is  unwrapped,  care  being  taken  not  to  loosen 
the  paraffine  cast  from  the  brass  plug,  and  cast  and  ping  toge- 
ther are  then  pushed  into  the  barrel  and  holder,  and  each  sec- 
tion is  cut  by  a  sidelong  sweep  of  the  cutter.  It  is  usual  in 
cutting  sections  to  flood  the  surface  of  the  tissue  and  the  blade 
of  the  knife  with  alcohol,  so  that  the  section,  in  cutting,  floats 
freely  over  the  blade. 

"  In  this  apparatus,  however,  from  the  great  length  of  the 
knife,  and  from  the  fact  that  its  edge  is  raised  off.  the  surface  of 
the  holder,  this  procedure  is  impracticable ;  but  I  find  that  I  get 
even  more  perfect  sections  by  the  plan  of  cutting  dry — that  is, 
without  flushing  the  surface  of  the  tissue  with  any  fluid.  It  will 
be  seen  in  the  figure  that  the  knife  is  set  at  a  slight  angle  in  the 
frame ;  and  this  obliquity  seems  to  give  the  section  a  tendency 
to  curl  away  from  the  knife-blade  in  the  cutting,  so  that  in  this 
dry  process  there  is  not  only  no  more,  but  there  is  actually  less 
danger  than  by  the  wet  method  of  the  section  clinging  to  the 
blade,  and  so  getting  torn.  But  here  the  preliminary  impreg- 
nation of  the  tissue  with  oil  of  cloves  is  essential ;  for,  were  it  in 
alcohol,  the  microscopically  thin  section  would  instantly  become 
ruinously  dry  as  soon  as  cut.  The  oil  of  cloves,  however,  from 
its  very  slight  volatility,  keeps  the  tissue  of  the  section  moist 
until  it  can  be  transferred  to  a  fluid.  But  it  will  not  do  so  long, 
and  hence  the  moment  a  section  is  cut  it  should  be  promptly 
seized  and  dropped  into  fluid  ;  and  if,  from  imperfect  impreg- 
nation before  embedding,  the  surface  of  the  cut  tissue  looks  dry 


1.16  SECTION    SIXTH. 

it  should  be  moistened  only  by  a  touch  of  a  camel's-hair  brush 
dipped  in  oil  of  cloves.  If  the  sections  are  not  to  be  stained, 
they  are  dropped  into  turpentine  as  soon  as  cut ;  this  dissolves 
the  adhering  wax  or  parafhne  very  promptly  if  slightly  warmed, 
and  the  sections  are  then  ready  for  examination  or  mounting. 
If  they  are  to  be  stained,  they  are  put  into  alcohol  instead  of 
turpentine.  This  in  a  few  minutes  dissolves  out  the  oil  of  cloves, 
and  the  sections  are  then  put  at  once  into  the  carmine  staining 
fluid. 

"  The  wood-cut  represents  two  accessory  pieces  of  apparatus 
that  have  not  been  alluded  to.  Fig.  III.  represents  a  secondary 
barrel  with  a  half-inch  bore,  which  can  be  screwed  into  the 
bottom-piece  of  the  main  barrel  to  diminish  its  size  when  any 
small  pieces  of  tissue  are  to  be  embedded.  It  has  a  plug  made 
to  fit  it  similar  to  the  large  plug  of  the  main  barrel.  Fig.  II.  is  a 
simple  and  ingenious  contrivance,  devised  by  Mr.  Wale,  the 
maker  of  the  instrument,  for  holding  hard  substances  which  wrill 
bear  squeezing,  and  which,  therefore,  it  is  not  necessary  or  desi- 
rable to  embed,  such  as  cartilage,  horn,  wood,  etc.  It  consists 
simply  of  a  brass  plug,  made  to  fit  the  barrel  of  the  section- 
cutter,  hollow,,  but  with  the  bore  slightly  conical,  and  with  a 
screw-thread  cut  on  its  face.  A  few  wedge-shaped  pieces  of 
soft  wood  of  different  sizes,  roughly  whittled  out,  complete  the 
apparatus.  Supposing  a  stick  of  wood  is  to  be  operated  on,  it 
is  grasped  between  two  of  the  wedges  of  the  right  size,  being 
allowed  to  project  somewhat  above  their  tops,  the  whole  pressed 
firmly  into  the  conical  bore  of  the  plug,  and  with  a  turn  or  two 
the  soft  wood  of  the  wedges  is  tightly  grasped  by  the  screw- 
thread  of  the  plug,  and  the  object  to  be  cut,  tightly  jammed 
between  the  wedges,  is  immovably  fixed.  Sections  can  be  cut 
from  the  projecting  portion  in  the  usual  way.  It  may  be 
remarked,  in  passing,  that  the  cutter  for  anatomical  tissues 
must  not  be  used  for  hard  substances.  For  these  a  strong, 
heavy  knife  or  chisel  of  less  brittle  temper  is  to  be  employed. 

"  In  conclusion,  it  may  not  be  amiss  to  state  that  the  section- 
cutter  and  accessories  can  be  obtained  (to  order)  of  Messrs. 
Hawkins  &  Wale,  physical  instrument  makers,  Stevens'  Insti- 
tute of  Technology,  Hoboken,  New  Jersey.  Price  $30,  or, 


THE    PREPARATION    OF    MICROSCOPIC    OBJECTS.         117 

without  the  knife-frame,  $20.  The  knife  is  a  simple  affair  and 
can  be  made  by  any  first-class  manufacturing  cutler  from  the 
dimensions  given  above.  Mine  was  made  by  Mr.  A.  Eiekhoff, 
3S1  Broome  Street,  New  York,  price  $3." 

This  instrument,  when  constructed  and  employed  in  the 
manner  above  described,  affords  better  results  than  any  other 
with  which  I  am  acquainted.] 

Peculiar  difficulties  present  themselves  in  making  thin 
sections  from  very  small  objects,  as  they  cannot  be  held  in  the 
fingers  of  the  left  hand,  like  more  substantial  masses.  Moist 
substances  are  therefore  placed  in  others  of  greater  size  ;  thus, 
for  example,  the  spinal  cord  of  a  small  mammalia  is  placed  in 
that  of  a  larger  creature.  Small  objects  may  also  be  advantage- 
ously placed  in  a  thick  solution  of  gum-arabic,  or  embedded  in 
a  mixture  of  wax  and  oil  (Strieker),  in  paraffine,  or  in  a  mixture 
of  glycerine  and  gelatine  (Klebs). 

1.  Embedding  in  gum.     A  paper  cone  or  box  is  to  be  filled 
with  a  very  concentrated  solution  of  gum-arabic  ;  in  this  mass  is 
placed  the  object,  from  which  the  water  has  been  drawn  out  by 
means  of  alcohol.     The  whole  is  then  to  be  placed  in  alcohol 
for  two  or  three  days,  and  is  then  in  a  condition  proper  for  cut- 
ting.     The  sections  are  to  be  washed  out  with  water. 

2.  Embedding  in  a  mixture  of  wax  and  oil.     Equal  parts 
of  each  are  to  be  warmed  in  a  porcelain  dish  till  they  become 
fluid,  and  the  mixture  is  then  poured  into  a  paper  box.     The 
preparation  is  to  be  deprived  of  its  water  with'  alcohol,  and 
rendered  transparent  by  means  of  an  ethereal  oil ;  it  is  then 
placed  in  the  mixture,  and  is  ready  for  cutting  as  soon  as  the 
latter  has  become  cold.     The  sections  are  to  be  washed  out  in 
oil  of  turpentine. 

3.  Embedding  in  paraffine.     A  cavity,  made  in  a  piece  of 
paraffine,  is  partially  filled  with  melted  paraffine.     In  the  latter 
is  placed  the  object,  which  has  been  hardened  in  chromic  acid 
and  alcohol.     Paraffine  is  again  poured  in,  and  the  whole  may 
afterwards  be  placed  in  alcohol.     In  many  cases  it  is  sufficient 
to  drop  a  little  melted  paraffine  on  to  a  slip  of  gutta-percha, 
place  the  object  on  it,  and  cover  the  latter  by  dropping  on  a 
little  more  paraffine  (His). 


118  SECTION    SIXTH. 

4.  Embedding  in  a  mixture  of  glycerine  and  gelatine. 
Alcohol  or  chromic  acid  preparations  may  be  placed  in  a 
mixture  composed  of  about  one  volume  of  a  very  concen- 
trated solution  of  isinglass  and  half  a  voline  of  pure  glycerine. 
The  whole,  when  cooled,  is  to  be  replaced  in  chromic  acid  or^ 
alcohol,  where  the  preparation  and  the  gelatine  become  suffi- 
ciently hard. 

For  very  hard  substances,  such  as  bones  and  teeth,  the 
knife  is  no  longer  serviceable  for  making  thin  sections.  In 
such  cases  a  small  saw  with  a  watch-spring  blade  is  to  be 
used,  and  the  section  is  to  be  ground  down  on  a  whetstone. 
This  can  be  best  and  most  rapidly  accomplished  with  a  rotary 
stone. 

The  ordinary  camel' s-hair  pencil  is  an  indispensable  imple- 
ment for  the  histologist.  In  addition  to  its  usefulness  for  re- 
moving dust  from  the  lenses  of  the  microscope,  it  is  also  very 
extensively  used  in  preparing  specimens.  It  is  the  best  thing 
to  use  for  removing  foreign  bodies  and  fragments  of  tissue  from 
the  surface  of  preparations,  and  for  spreading  out  thin  and  de- 
licate sections  on  the  slide.  When  it  is  necessary  to  remove 
from  an  object  the  cellular  elements,  which  often  occur  in  such 
great  profusion  as  to  conceal  the  entire  arrangement  of  its  super- 
structure, this  may  be  much  better  accomplished  by  the  pencil- 
ling method,  originated  by  His,  than  with  the  stream  from  a 
wash-bottle.  The  specimen  is  to  be  thoroughly  moistened  and 


Fig.  71.    Pencilling  microscopic  objects. 


covered  with  fluid  (generally  glycerine  and  water),  and  then 
brushed  with  a  camel's-hair  pencil  of  medium  size,  the  perpen- 
dicular strokes  rapidly  following  each  other  (fig.  71).  The  fluid 


THE    PREPARATION    OF    MICROSCOPIC    OBJECTS.        119 

gradually  thickens  and  the  tissue  becomes  transparent.  After 
a  few  minutes  the  preparation  is  to  be  turned  over,  and 
the  process  repeated  on  its  other  surface.  In  this  mari- 
ner, and  occasionally  removing  the  old  fluid  and  repla- 
cing it  with  new,  the  isolated  frame-work  gradually 
makes  its  appearance.  It  is  also  very  serviceable  to 
pencil  an  object  while  it  is  floating  in  a  larger  quantity 
of  fluid — for  example,  in  one  of  the  above-mentioned 
glass  boxes.  A  considerable  amount  of  patience  is  ne- 
cessary to  make  good  preparations  in  this  way,  and  still 
more  to  obtain  the  proper  consistence  of  the  object  to 
be  prepared.  When,  it  is  not  sufficiently  hardened,  it 
becomes  filled  "with  rents,  even  when  the  brush  is  care- 
fully used.  Such  tissues  generally  become  quite  service- 
able after  hardening  for  a  day  or  two  longer.  It  is 
much  worse  when  an  over  hardened  tissue  is  to  be  pre- 
pared in  this  manner.  In  such  cases  one  can  obtain  only 
an  imperfect  preparation  or  none  at  all ;  it  is  no  longer 
possible  to  remove  the  cells.  As  a  rule,  the  thing  is 
then  to  be  entirely  abandoned,  for  a  subsequent  soften- 
ing rarely  leads  to  success.  Billroth  has  also  given  some 
particular  directions  on  the  pencilling  method. 

A  strip  of  bibulous  paper  may  be  used  for  removing    i^lfe  pt 
superfluous  fluids  from  the  slides.     It  is  more  conve-    pette* 
nient  to  use  a  small  pipette  (fig.  72),  an  instrument  which  can 
hardly  be  dispensed  with  in  making  permanent  specimens. 


0ection 


FLUID  MEDIA  AND  CHEMICAL  REAGENTS.     TTTIIITION. 

ANIMAL  tissues  are  comparatively  seldom  examined  in  a  sim- 
ple dry  condition,  but,  as  a  rule,  a  fluid  is  added.  This  fluid 
may  act  indifferently,  although  this  is  more  rarely  the  case  than 
is  generally  imagined;  it  may  act  chemically  on  the  object;  it 
may  withdraw  fluid  from  it,  or  allow  fluid  to  pass  into  it,  so  that 
shrinking  or  swelling  results  ;  finally,  it  may  produce  changes 
in  the  refractive  conditions  of  the  tissue. 

Let  us  first  investigate  the  latter.  The  greater  the  contrast 
between  the  refractive  power  of  the  object  and  that  of  the  sur- 
rounding medium,  the  sharper  will,  the  former  appear.  Thus 
many  delicate  structures  may  be  most  distinctly  recognized 
when  dry  and  surrounded  by  atmospheric  air,  while  the  addi- 
tion of  water,  by  changing  the  refraction  of  the  light,  perhaps 
entirely  prevents  the  details  from  appearing,  or  renders  them 
very  indistinct.  Many  textural  relations  of  animal  tissues  are 
exceedingly  difficult  to  recognize,  in  consequence  of  the  slight 
difference  between  their  refractive  power  and  that  of  the  sur- 
rounding water.  "We  must,  therefore,  coincide  with  Ilarting, 
who  says,  the  discovery  of  a  fluid  medium  of  less  refractive 
power  than  water  would  afford  very  valuable  assistance  in  many 
investigations.  Other  methods  of  rendering  many  things 
darker  and  more  distinct,  such  as  tinging  the  tissues,  the  appli- 
cation of  reagents  which  coagulate  and  therefore  darken  them, 
are  discussed  further  on.  Certain  reagents,  acetic  acid  for  ex- 
ample, act  very  advantageously  by  rendering  a  constituent  part, 
as  for  instance  the  nucleus  of  a  cell,  darker,  while  the  refractive 
power  of  the  surrounding  substance  is  diminished.  The  action 
of  acetic  acid  on  connective  tissue  affords  us  an  instructive 
example  of  how  little  one  is  justified  in  assuming,  from  a  single 


FLUID    MEDIA    AND    CHEMICAL    EEAGENTS.  121 

method  of  investigation,  that  there  is  nothing  in  the  field  because 
there  is  nothing  to  be  seen  there.  By  causing  the  finest  fibres 
into  which  the  intercellular  substance  of  connective  tissue  is 
split  up  to  swell,  their  refractive  power  and  that  of  the  surround- 
ing fluid  is  rendered  similar,  so  that  one  might  think  that  the 
fibrillse  had  been  dissolved  by  the  reagent,  were  it  not  for  other 
methods  which  cause  the  reappearance  of  the  fibres  which  had 
been  rendered  invisible  by  the  acid. 

On  the  other  side,  the  necessity  often  makes  itself  felt  of 
rendering  objects  which  are  too  dark,  and  therefore  no  longer 
recognizable,  as  transparent  as  possible  by  means  of  a  fluid 
which  refracts  the  light  strongly.  Hence  strong  solutions  of 
sugar,  gum,  or  albumen  may  be  used,  wrhen  it  is  necessary  to 
clear  up  tissues  which  are  saturated  with  water.  In  modern 
times  we  have  learned  to  recognize  in  glycerine  an  invaluable 
accessory  of  this  nature ;  creasote  also  deserves  recommendation. 
Tissues  which  are  free  from  water  are  more  permanently  cleared 
up  by  means  of  turpentine  oil,  Canada  balsam,  or  anis  oil.  While 
the  index  of  refraction  of  water  is  1.336,  glacial  acetic  acid  has 
that  of  1.38,  pure  glycerine  1.475,  equal  parts  of  glycerine  and 
water  1.40,  oil  of  turpentine  1.476,  Canada  balsam  1.532-1.549, 
and  that  of  anis  oil  is  even  1.811. 

How  much  the  appearance  of  a  microscopic  object  is  deter- 
mined by  the  refractive  power  of  the  fluid  medium  is  self-evi- 
dent. A  small  glass  rod  lying  in  water  can  be  readily  recog- 
nized with  exactness,  in  consequence  of  the  difference  of  the 
exponents  of  refraction.  When  it  is  placed  in  Canada  balsam, 
whereby  they  become  nearly  similar,  the  glass  rod  ceases  to 
glisten  and  can  only  with  great  attention  be  distinguished  from 
a  flat  band.  If  anis  oil  be  selected  as  a  medium,  an  image  is 
received  as  though  there  was  a  cavity  in  the  oil  (Welcker). 

The  necessity  for  the  discovery  of  an  actually  indifferent  fluid 
medium,  that  is,  one  which  does  not  change  the  tissue,  cannot 
be  impressed  with  sufficient  force  on  the  hearts  of  microseo- 
pists.  We  have  fallen  into  the  beaten  track  of  ascribing,  with 
generous  credulity,  to  water  such  a  role,  but  which,  in  fact,  it 
does  not  play.  It  is  conceded  that  a  small  fraction,  at  the  most, 
of  the  animal  tissues  make  an  exception,  and  the  energetic  ac- 


122  SECTION    SEVENTH. 

tion  of  water  on  the  colored  blood  corpuscles  and  the  elements 
of  the  retina  cannot  be  denied.  That  the  number  of  tissues 
affected  by  water  is  much  greater,  and  that  very  few  can  remain 
indifferent  to  it,  is  very  clear  to  a  few  persons,  but  is  by  110 
means  generally  known.  While  so  many  have  recently  occu- 
pied themselves  with  the  endosmatic  processes  of  physical 
physiology,  in  the  particular  domain  of  microscopy,  no  investi- 
gation of  this  process  has  yet  been  commenced. 

Theory  requires  that  each  constituent  of  the  body  should  be 
examined  in  a  fluid  medium  which  resembles,  in  respect  to 
quality  and  quantity,  the  fluid  which  saturates  the  living  tissue. 
Naturally,  this  requirement  cannot  be  completely  fulfilled  in 
practice ;  our  aim  should  be  to  approach  it  as  nearly  as  possible. 

Saliva,  vitreous  humor,  arnniotic  liquor,  serum,  and  diluted 
albumen  are  generally  recommended  as  suitable  media  for  the 
investigation  of  delicate  changeable  tissues,  and,  in  certain 

&  O  *  ' 

cases,  they  accomplish  their  object  in  a  satisfactory  manner. 
But  do  not  expect  them  to  suffice  for  every  case.  Not  unfre- 
quently  one  and  the  same  tissue  of  different  species  of  animals 
reacts  differently  with  the  same  fluid  medium,  as  may  be  seen 
with  the  blood  corpuscles.  M.  Schultze  has  communicated  to 
us  an  important  and  readily  proved  observation  of  Landolt's, 
that  animal  fluids  may  be  preserved  from  decomposition  for  a 
long  time  by  the  addition  of  a  small  piece  of  camphor. 

A  physical  examination  made  by  Graham  presents  us  with  a 
key  to  the  nature  of  these  indifferent  fluids. 

In  an  exceedingly  interesting  work  (Annalen  der  Chemie  uiid 
Pharmazie,  Bd.  121,  S.  1),  this  scholar  some  time  ago  called 
attention  to  the  fact,  that  two  groups  of  substances,  which  he 
has  designated  by  the  names  of  Crystalloids  and  Colloids,  are 
to  be  distinguished  according  to  their  power  of  diffusion.  The 
former,  belonging  to  the  crystalline  bodies,  diffuse  rapidly  and 
remind  one,  in  this  regard,  of  more  volatile  substances ;  the 
latter,  characterized  by  their  inability  to  assume  the  crystalline 
condition,  show  a  very  slight  diffusibility.  Among  the  organic 
bodies  may  be  numbered,  for  example,  gum,  starch,  dextrine, 
mucus,  albumen,  and  gluten. 

When  a  column  of  water  is  placed  over  a  solution  which  con- 


FLUID    MEDIA   AND    CHEMICAL    KE  AGENTS.  123 

tains  both  these  varieties  of  substances,  chloride  of  sodium  and 
albumen,  for  instance,  the  salt  will  penetrate  to  the  uppermost 
stratum  of  the  fluid,  while  the  albumen,  in  consequence  of  its 
slight  diffusibility,  will  not  pass  anything  like  so  far  upwards, 
so  that  the  upper  strata  remain  free  from  it.  Gelatinous  mat- 
ters from  the  colloid  series,  such  as  mucus,  for  instance,  permit 
a  very  easy  passage  to  readily  diffusible  matters,  but  resist  very 
energetically  that  of  less  diffusible  ones,  and  do  not  let  other 
colloid  matters  pass  through.  By  means  of  suitable  membranes 
of  this  kind,  crystallized  matters  may  be  separated  from  colloid 
substances,  and  the  latter  may  be  thoroughly  purified  in  this 
way.  According  to  Graham's  observations,  readily  diffusible 
substances,  such  as  chloride  of  sodium,  even  spread  themselves 
through  a  stiff  jelly  with  almost  the  same  facility  as  in  pure 
water. 

It  is  self-evident  that  these  investigations  are  of  great  sig- 
nificance in  connection  with  the  processes  of  diffusion  in  the 
tissues  composed  of  colloid  substances. 

The  above-mentioned  indifferent  fluids  now  appear  to  us  in  a 
new  light.  They  always  contain  colloid  and  crystalloid  sub- 
stances. Vitreous  humor  contains  987  parts  of  water  to  about 
4.6  parts  of  colloid  matter,  7.8  of  crystalloid  substance  (that  is, 
chloride  of  sodium).  In  amniotic  liquor  about  the  same  pro- 
portions are  met  with.  In  1000  parts  occur  about  3.8  of  colloid 
substance  (albumen),  5.8  of  salts,  together  with  3.4  of  urea.  In 
serum  we  have  about  8.5  per  cent,  of  colloid  and  1  of  crystalloid 
substances. 

After  what  has  been  said  it  is  unnecessary  to  remark  that 
fluids  which  contain  only  crystalloid  or  only  colloid  matters  can 
make  no  claim  to  the  character  of  truly  indifferent  media, 
although  they  may  not  perceptibly  alter  the  contours  and  forms 
of  the  tissue  elements  for  a  long  time. 

Accordingly,  it  has  very  properly  been  suggested  that  the 
microscopist  should  always  have  such  indifferent  fluids  in  readi- 
ness, the  more  so  as  solutions  of  albumen  or  liquor  amnii  may 
readily  be  preserved  from  decomposition  for  months  by  placing 
a  piece  of  camphor  in  them  (M.  Schultze).  A  solution  of  albu- 
men, of  known  quantitative  composition,  purified  by  means  of 


124  SECTION   SEVENTH. 

Graham's  dialyser,  and  to  which  a  certain  quantity  of  chloride 
of  sodium  is  to  be  added,  may  be  preserved  with  the  aid  of  a 
piece  of  camphor,  and  will  be  very  serviceable  if  diluted  with 
water  each  time  that  it  is  used.  It  is  useless,  however,  for  the 
preservation  of  large  pieces  of  tissue. 

It  is  obvious  that  the  addition  of  colloid  substances  to  solu- 
tions of  the  salts  ordinarily  used  by  microscopists  also  deserves 
a  trial. 

Schultze  has  more  recently  recommended,  in  the  warmest 
manner,  an  albuminous  fluid  tempered  with,  iodine — and  in  fact 
according  to  my  own  experience  it  is  exceedingly  serviceable. 
"  Jod-serum,"  as  he  calls  it,  consists  of  the  amniotic  fluid  of  the 
embryo  of  the  ruminantia,  to  which  a  concentrated  tincture  of 
iodine  or  a  strong  solution  of  iodine  in  hydriotic  acid  is  added. 
About  six  drops  are  to  be  added  to  the  ounce  while  shaking  the 
mixture.  The  color  of  the  solution  is  at  first  Avine  yellow,  but 
after  a  few  hours  it  becomes  paler ;  this  paleness  afterwards 
increases,  and  the  subsequent  addition  of  a  few  drops  of  the 
iodine  solution  becomes  necessary.  Onr  mixture  forms  an  ex- 
cellent fluid  for  the  examination  of  delicate  fresh  tissues,  and  is 
also  a  very  good  and  very  preservative  macerating  medium, 
acting  in  this  way  even  for  hours  or  days.  AVe  must  here  give 
a  piece  of  advice  which  is  of  great  importance  in  the  numerous 
macerations  of  this  kind  which  are  necessary,  namely,  to  have 
the  piece  which  is  to  be  placed  in  them  very  small,  and  the 
quantity  of  the  fluid  as  large  as  possible.  An  artificial  mixture, 
composed  of  1  ounce  of  the  white  of  an  egg,  0  ounces  of  water, 
2  scruples  of  chloride  of  sodium,  with  the  corresponding  quan- 
tity of  tincture  of  iodine,  appears  to  form  a  substitute. 

In  the  use  of  water,  in  which  case  distilled  water  should  be 
employed,  the  swelling  of  the  delicate  tissues  is,  possibly,  very 
considerable ;  not  unfrequently  they  may  even  be  more  perma- 
nently altered  ;  so  that  it  is  advisable  for  any  one  who  would 
protect  himself  from  deception  to  try  other  fluid  media  also, 
in  order  to  decide  what  has  remained  unaltered  in  his  micro- 
scopic image,  and  what  has  been  acted  upon  by  the  water. 

Glycerine  has  already  been  mentioned  several  times  in  these 
pages.  Together  with  its  property  of  rendering  tissues  trans- 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.  125 

parent,  which  is  of  inestimable  value  for  such  as  have  been 
hardened  and  rendered  opaque  by  reagents,  it  forms  a  preser- 
vative, though  not  indifferent  medium  for  many  tissues,  and 
even  for  the  prolonged  preservation  of  larger  pieces.  Its 
power  of  rendering  tissues  transparent  may  be  restrained  by 
the  addition  of  water.  A  mixture  recommended  by  Schweigger 
Seidel,  composed  of  1  part  of  pure  glycerine  to  9  parts  of  dis- 
tilled water,  is  useful  for  the  examination  of  numerous  objects. 
Many  delicate  structures  shrink  in  glycerine,  it  is  true,  but 
after  longer  action  they  again  become  tilled  out  and  clear.  A 
number  of  really  chemical  reagents — for  example,  acetic  acid, 
formic  acid,  iodine,  tannin,  and  chromate  of  potash — may  be  ad- 
vantageously combined  with  it,  and  it  also  forms  an  ingredient 
of  cold  injection  masses  (see  below).  Finally,  it  presents  the 
best  fluid  for  mounting;  moist  tissues. 

O 

Nowadays  chemical  reagents  are  very  frequently  employed 
in  microscopic  investigations,  and  the  number  of  these  which 
are  necessary  for  various  histological  and  medical  purposes  is  by 
no  means  small.  They  are  the  same  as  are  generally  used  for 
zoochernical  investigations. 

They  are  chiefly  employed  in  microscopical  investigations 
when  we  wish  to  ascertain  the  nature  of  amorphous  and  crystal- 
line deposits,  the  disposition  of  elementary  granules,  or  the  con- 
stitution of  tissue  elements.  The  ordinary  solutions,  naturally 
from  a  reliable  source,  are  used  for  these  processes.  Their 
application,  however,  requires  great  foresight  with  regard  to  the 
microscope,  if  one  would  protect  it  from  injury.  AVe  therefore 
repeat  certain  precepts  which  have  already  been  given.  The 
lenses  should  never  be  wetted  with  the  fluids.  Only  the  weaker 
objectives,  with  long  foci,  are  to  be  used,  and  the  covering 
glasses  should  be  as  large  and  broad  as  possible.  In  order  to 
prevent  the  fluids  from  running  on  to  the  stage,  the  slides  should 
not  bo  too  narrow.  I  generally  cover  the  stage  completely  with 
a  glass  plate  of  the  same  size  with  ground  edges,  a  precautionary 
measure  worthy  of  recommendation  to  those  who  have  the  protec- 
tion of  their  instruments  at  heart.  When  the  stage  consists  of  a 
plate  of  ground  black  glass,  as  is  the  case  with  some  of  the  older 
microscopes,  it  is  very  convenient  for  chemical  examinations. 


126  SECTION    SEVENTH. 

The  reagent  is  either  simply  added  to  the  microscopic  pre- 
paration by  means  of  a  pointed  glass  rod,  the  covering  glass 
being  previously  removed,  or  the  fluid  is  allowed  to  flow  under 
the  edge  of  the  cover  to  the  object ;  it  may  also  be  allowed  to 
enter  gradually,  in  order  to  observe  the  successive  changes  which 
occur  during  its  action.  A  thread  of  lint,  one  end  of  which  is 
placed  under  the  cover,  may  be  used  as  a  conductor,  or  two 
very  narrow  strips  of  bibulous  paper  may  be  placed  at  opposite 
borders  of  the  cover,  one  of  which  serves  to  remove  the  old 
fluid  while  the  new  is  being  introduced  by  the  other,  whereby, 
however,  the  entrance  of  the  reagent  is  more  rapid  and  its 
effects  are  more  energetic. 

More  important  than  this  momentary  use  of  chemical  re- 
agents is  the  continuous  application  of  the  same  for  a  longer 
period  as  hardening,  preservative,  or  macerating  fluids.  Animal 
tissues  are  frequently  allowed  to  remain  in  the  solutions  for 
hours  or  even  days  consecutively.  This  method  has  been  fre- 
quently used  in  modern  times,  and  to  it  is  due  most  of  the 
knowledge  that  has  been  obtained  in  latter  years  concerning  the 
tissues,  etc.,  of  the  human  body.  Its  perfection 
should,  therefore,  be  of  great  interest  to  every  in- 
vestigator. Its  application,  however,  requires  an 
exact  procedure.  Above  all  things,  one  should 
avoid  all  such  old  delusions  as  when  putting  a  tissue 
in  acetic  or  sulphuric  acid,  or  in  solutions  of  potash 
or  soda,  to  disregard  the  strength  of  the  solutions, 
or  the  relative  volume  of  the  tissue  to  that  of  the 
fluid.  Hence  it  is  the  duty  of  every  one  who  em- 
ploys any  of  these  chemical  methods,  or  recom- 
mends a  new  one,  to  describe  his  process  accurately. 
A  watch-glass,  or  a  small  shallow  glass  box  may 
be  used  when  the  process  is  to  continue  but  a  few 
moments.  For  more  continued  action,  small  bot- 
tles with  wide  mouths  and  ground  glass  stoppers 
are  to  be  USC(1,  or>  still  better,  small  graduated 
cylinder  glasses  (fig.  73).  The  vessels  should  al- 
ways be  labelled,  to  avoid  confusion,  to  remember  the  date, 
etc. 


FLUID    MEDIA    AND    CHEMICAL    KE  AGENTS.  127 

"We  will  now  proceed  to  the  consideration  of  the  reagents 
which  are  at  present  most  frequently  used. 

1.)  Among  the  strong  mineral  acids,  sulphuric,  muriatic,  and 
nitric  acids,  in  a  concentrated  form,  act  destructively  on  most 
histogenetic  substances.  Nevertheless,  they  afford  an  impor- 
tant means  of  isolating  certain  tissues,  inasmuch  as  they  dissolve 
their  connecting  or  cementing  substance,  and  also,  in  part,  the 
connective  tissue  which  occurs  in  them.  In  a  more  diluted  con- 
dition they  form  useful  hardening  solutions  for  various  tissues, 
while  with  a  still  higher  degree  of  dilution  we  obtain  the  action 
of  weak  acids  on  various  tissue  elements,  causing  them  to  become 
transparent,  to  dissolve,  or  to  swell  up.  In  this  way  these  acids 
may  constitute  very  important  macerating  mediums. 

Sidplmric  Acid. — The  purified  concentrated  English  sul- 
phuric acid,  non-fuming,  with  a  specific  gravity  of  1.85-1.S3,  is 
to  be  used. 

The  concentrated  acid  is  but  rarely  used.  Still  it  is  an  excel- 
lent auxiliary  in  the  investigation  of  the  horny  structures 
(the  cornified  epithelium,  the  nails,  and  hair),  for  isolating  the 
cells  of  these  tissues.  It  also  forms  alone,  or  combined  with 
iodine,  a  good  reagent  for  cholesterin  ;  the  latter  combination 
is  also  useful  for  cellulose  or  amyloid  substances.  Sugar  and 
sulphuric  acid  redden  many  organic  substances,  such  as  albu- 
minous and  amyloid  bodies,  oleic  acid,  etc. 

Strongly  diluted  sulphuric  acid  hardens  albuminous  tissues, 
acting  similarly  to  chromic  acid  (see  this).  It  has  the  ad  vantage 
over  the  latter  of  rendering  gelatinous  and  connective  tissues 
transparent,  and,  at  the  same  time,  so  consolidated  that  thin  sec- 
tions of  them  may  be  made.  Moreover,  less  depends  on  the 
accurate  concentration  of  sulphuric  acid  than  on  that  of  chromic 
acid.* 

When  connective  tissue  is  treated  for  twenty-four  hours  with 
highly  diluted  sulphuric  acid,  0.1  grin,  to  1000  grammes  of 

*  M.  Schultze,  who  has  presented  us  with  these  statements,  employs  an 
acid  of  1.839  specific  weight,  of  which  about  18  drops  make  1  gramme  and 
22  a  scruple.  He  recommends,  as  a  mean,  3  to  4  drops  to  1  ounce  of  water 
(with  extremes  of  1  to  10),  and  praises  its  effects  for  hardening  the  support- 
ing substances  of  the  central  organs  of  the  nervous  system,  of  the  retina,  and 
also  the  reticulated  tissues  of  the  lymph  glands  and  kindred  organs. 


128  SECTION    SEVENTH. 

water,  and  warmed  to  a  temperature  of  from  35°  to  40°  C.,  it  is 
resolved  into  gelatine ;  so  that  in  this  way  other  elements  are 
spared  as  much  as  possible,  and  may  be  isolated  from  connect- 
ive tissue.  Kiihne  has  employed  this  method  with  good  success 
for  muscular  fibres. 

Sulphurous  Acid. — It  has  been  recommended  by  Klebs  to 
add  a  small  quantity  of  sulphurous  acid  to  a  solution  of  cane- 
sugar  of  5  per  cent,  (one  drop  of  a  pretty  concentrated  solution 
of  the  former  to  one  ccm.  of  the  latter  fluid)  for  loosening  epi- 
thelium, and  for  rendering  connective  tissue  transparent  without 
causing  infiltration. 

Nitric  Acid. — The  pure  concentrated  nitric  acid  of  the  chem- 
ical laboratories  of  1.5  specific  weight  may  be  used,  or  acids 
containing  more  water,  with  a  specific  weight  of  1.4:  to  1.2  (the 
latter  is  the  officinal  nitric  acid). 

The  former  (1.5),  mixed  with  chlorate  of  potash,  destroys 
connective  tissue  in  a  short  time,  and  is  therefore  a  good  medi- 
um for  isolating  muscular  fibres  (Kiiline).  This  may  also  be 
accomplished,  though  more  slowly,  with  weaker  acids.  This 
reagent,  recommended  by  Schultze,  is  frequently  used  by  bota- 
nists ;  it  deserves  further  trial  for  animal  tissues.  Caution  in  its 
application  is  always  advisable. 

The  property  of  nitric  acid  of  coloring  albuminous  matters 
yellow  is,  in  general,  rarely  made  use  of  in  microscopical  inves- 
tigations. 

Strong  nitric  acid  serves  to  isolate  connective  tissue  corpuscles, 
bone  corpuscles  and  their  processes,  as  also  the  dentinal  canals. 

Nitric  acid  of  20  per  cent,  was  recommended  many  years  ago 
by  Eeichert  and  Paulscn  as  a  medium  for  the  isolation  and 
recognition  of  the  elements  of  the  smooth  muscles. 

Diluted  nitric  acid  (5  to  10  per  cent.)  is  also  used  for  the 
extraction  of  the  so-called  bone  earths  (a  mixture  of  lime  and 
magnesia  salts)  from  calcified  cartilages  and  bones ;  although 
hydrochloric  acid  and,  still  better,  chromic  acid  (see  this)  may 
be  employed  for  this  purpose. 

In  a  condition  of  extreme  dilution  (0.1  per  cent.),  nitric  acid 
has  recently  been  tried  by  Kolliker  for  rendering  muscles  trans- 
parent. It  does  not  present  any  special  advantages. 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.          129 

Muriatic  Acid. — Pure  muriatic  acid,  thoroughly  saturated 
with  chlorine,  of  1.19  specific  weight,  is  not  at  all,  or  only 
rarely,  used  undiluted  for  histological  investigations.  Strong 
muriatic  acid  is  frequently  used  for  dissolving  the  intercellular 
substance  of  connective  tissue  organs,  and  for  isolating  the  con- 
nective tissue  corpuscles  and  their  radiating  tubular  systems,  as  in 
the  cornea,  the  teeth,  and  bones.  This  action  generally  requires 
some  time,  occasionally  a  number  of  days.  By  this  means  the 
intercellular  substance  of  the  muscles  (Aeby)  and  of  the  urinary 
tubes  (Henle)  has  been  dissolved.  An  acid  which  has  been  di- 
luted with  water  till  it  ceases  to  smoke,  is  frequently  used  for  this 
purpose.  The  time  required  is  generally  12-14  hours  ;  weaker 
acids  act  more  slowly.  The  object  is  then  to  be  washed  out  and 
macerated,  for  a  day  at  least,  in  distilled  water.  When  this 
process  succeeds,  the  whole  may  be  rapidly  and  beautifully  iso- 
lated by  the  careful  use  of  the  needles.  An  important  modifi- 
cation of  the  above-mentioned  process  consists  in  boiling  pieces 
of  the  kidney  for  6-8  hours  in  alcohol  of  90  per  cent.,  to  which 
^  to  f  per  cent,  by  volume  of  purified  muriatic  acid  of  the 
greatest  possible  strength  has  been  added.  The  operation  is  to 
be  conducted  on  the  water-bath,  in  an  alembic  provided  with  a 
cooling  apparatus  (Ludwig  and  Zawarykiii).  This  process  is 
also  useful  for  other  glands.  Tomsa  has  recommended  boiling 
for  one  or  two  days,  and  subsequent  washing  in  water  for  iso- 
lating the  cutaneous  nerves.  Size  injections  with  Prussian  blue 
retain  their  color  and  the  consistence  of  the  vessels  with  both 
methods.  Muriatic  acid,  of  the  same  dilution  as  the  nitric  acid, 
may  be  used  for  extracting  the  bone  earths.  In  a  high  degree 
of  dilution  (0.1  per  cent.)  it  forms  a  medium  for  macerating 
connective  tissue  and  rendering  it  transparent,  the  cells  and 
elastic  tissue  of  which  then  appear  very  beautifully.  Our  acid 
also  dissolves  the  fleshy  substance  of  muscular  fibres,  and  may 
thus  be  advantageously  employed  in  the  examination  of  mus- 
cular tissues. 

Chromic  Acid. — Since  Hannover,  in  £he  year  1840,  recom- 
mended chromic  acid  to  microscopists  as  a  medium  for  harden- 
ing animal  tissues,  its  reputation  has  been. constantly  increasing, 
especially  since  the  inaccurate  method  of  estimating  the  strength 
9 


130  SECTION    SEVENTH. 

of  its  solutions  from  their  color  has  been  abandoned  for  that  by 
means  of  the  scales. 

It  is  extremely  useful  for  hardening  the  brain  and  medulla 
oblongata,  as  well  as  the  peripheral  nervous  apparatus.  Not 
unfrequently  it  is  more  serviceable  than  alcohol,  which  exerts 
too  great  a  change  on  these  tissues,  while  the  latter  is  either 
equal  or  preferable  to  the  former  for  other  organs,  such  as  most 
glandular  structures,  the  intestinal  canal,  etc. 

Well-crystallized  chromic  acid,  as  free  as  possible  from  sul- 
phuric acid,  should  always  be  used.  It  should  be  kept  in  a  well- 
closed  vessel,  in  a  dry  place,  and  the  portion  to  be  used  should 
be  dried  over  sulphuric  acid  previous  to  its  employment.  To 
economize  time,  a  considerable  quantity  of  a  strong  solution 
may  be  kept  on  hand,  which  may  be  rapidly  diluted  to  any  de- 
gree desired  by  means  of  a  graduated  measure.  I  dissolve  2 
grammes  in  98  grammes  (or  cubic  centimetres)  of  distilled  water, 
so  that  a  2  per  cent,  solution  stands  ready. 

For  hardening  purposes  a  chromic  acid  solution  of  from  0.5 
to  1,  or,  at  most  2  per  cent,  is  necessary.  In  no  case  should  a 
higher  degree  of  concentration  be  used,  and  generally  the  weaker 
ones  work  better.  Very  fresh  tissues  usually  require  weaker, 
older  pieces  somewhat  stronger  solutions.  Very  fine  results 
may  be  obtained,  especially  when  the  pieces  are  not  very  volu- 
minous, by  commencing  with  a  weak  solution  (about  0.2  per 
cent.),  and  then,  after  a  few  days,  changing  the  fluid  for  one  of 
stronger  concentration  (0.5  to  1  per  cent.),  in  which  the  object 
is  to  remain  for  days  and  weeks,  until  it  has  obtained  the  desired 
consistence.  Then — in  consequence  of  the  r  ^adiness  with  which 
fungi  are  formed  in  chromic  acid  solutions — the  hardened  pre- 
paration should  be  kept  in  diluted  alcohol. 

When  a  voluminous  organ  is  to  be  hardened  it  is  advisable, 
before  placing  it  in  the  chromic  acid,  to  drive  the  same  solution 
through  the  blood-vessels. 

However,  with  all  chromic  acid  operations,  very  much  de- 
pends on  the  proper  degree  of  concentration,  and  this  is  not  al- 
ways hit  upon  even  by  the  most  experienced ;  this  is  all  the 
more  so,  as  the  contamination  with  sulphuric  acid  is  quite  vari- 
able. Yery  voluminous  organs  may  present  a  hardened  peri 


FLUID    MEDIA    AND    CHEMICAL    KEAGENTS.          131 

phery,  while  the  interior  is  decomposed.  Portions  which  are 
over-hardened  have  their  tissue  elements  very  much  shrunken, 
and  are  often  found  to  be  so  hard  and  brittle  that  it  is  no  longer 
possible  to  make  thin  sections  from  them.  An  improvement 
may  sometimes  be  obtained  by  laying  the  piece  of  organ  in 
glycerine  for  several  days.  It  is  preferable  to  add  some  of  this 
to  the  chromic  acid  at  the  very  beginning. 

So  much  for  these  concentrated  hardening  solutions  of  chro- 
mic acid.  This  reagent  has,  however,  when  highly  diluted,  still 
another  and  more  important  property,  namely,  of  preserving 
the  finest  textural  relations  while  exerting  a  somewhat  macera- 
tive  action  on  them.  So  that  in  this  way  very  delicate  organi- 
zations, especially  in  nervous  tissues,  may  be  made  visible  which 
remained  completely  hidden  in  the  examination  of  the  fresh 
tissue.  For  this  very  reason  it  has  exerted  a  very  enduring  in- 
fluence in  the  histology  of  the  higher  nerves  of  sense,  to  which 
fact  the  works  of  M.  Schultze  especially  testify.  It  has  since 
been  used  with  success  for  the  investigation  of  the  central  organ 
of  the  nervous  system,  the  ganglia,  and  also  for  glandular  struc- 
tures. 

In  general,  according  to  present  experience,  only  a  concentra- 
tion of  from  j-  to  J-  of  a  grain  to  the  ounce  of  water,  that  is,  a 
solution  of  from  0.025  to  0.05  per  cent.,  is  applicable  for  this 
purpose,  and  in  fortunate  cases  the  desired  effect  is  accom- 
plished in  from  one  to  three  days.  Others  (Deiters,  J.  Arnold, 
Kiihne)  have  even  descended  to  solutions  of  from  0.02  to  0.01 
per  cent,  and  less — and  even  to  these  an  effect  cannot  be 
denied. 

The  volume  of  the  fluid  and  that  of  the  portion  of  tissue 
placed  in  it  are  here  of  greater  importance  than  for  simple 
hardening.  Generally,  when  the  latter  is  small  and  the  fluid 
plentiful,  the  action  is  naturally  more  energetic  and  rapid,  so 
that  in  this  case  the  limits  may  easily  be  exceeded.  It  is  proper, 
therefore,  not  to  select  too  small  a  piece,  and  not  to  add  too 
large  a  quantity  of  fluid.  When  the  object  is  too  small,  the 
same  effect  takes  place  as  with  stronger  solutions,  they  receive  a 
lively  yellow  color  and  become  opaque ;  when  of  the  proper 
proportions  they  become  paler  and  semi-transparent. 


132  SECTION    SEVENTH. 

We  have  already  mentioned  above  the  interesting  and,  in 
their  consequences  for  practical  microscopy,  very  important  ob- 
servations of  Graham  on  the  colloid  and  crystalloid  substances. 
Schultze  (who  was  the  first  among  German  histologists  to  com- 
prehend the  full  significance  of  Graham's  observations)  has 
properly  called  attention  to  the  fact  that  the  action  of  chromic 
acid  is  not  alone  concerned  in  this  case,  but  to  this  is  also  added, 
when  the  piece  is  large  and  the  quantity  of  fluid  moderate,  the 
preponderating  effect  of  the  colloid  substances  of  the  tissue ; 
such  as  blood,  mucus,  and  albumen.  Hence  a  fluid  results 
which  consists  conjointly  of  crystalloid  and  colloid  substances ; 
while  a  small  piece  of  tissue  placed  in  a  larger  quantity  of  chro- 
mic acid  solution  is  subjected,  almost  entirely,  to  the  action  of 
this  crystalloid  substance  alone. 

At  present  microscopic  technology  is  only  in  its  youth,  not  to 
say  childhood.  In  a  riper  period  such  combinations  will  cer- 
tainly play  an  important  role.  Schultze  informs  us  that  he  is 
making  investigations  relative  to  this  subject,  and  that  a  watery 
solution  of  gum-arabic  appears  to  be  suitable  as  a  colloid  sub- 
stance. May  he  soon  give  us  further  information  on  this  sub- 
ject ! 

Similar,  but  much  weaker  and  more  slowly  commencing  effects 
are  also  produced  by  bichromate  of  potash,  which  will  be  spoken 
of  further  below. 

Finally,  still  another  very  advantageous  use  has  been  made  of 
chromic  acid ;  namely,  for  extracting  the  earthy  salts  from  so- 
called  ossified  cartilage,  and  also  from  bones.  It  is  especially 
commendable  for  foetal  tissues.  Generally  it  is  necessary  to 
have  a  higher  degree  of  concentration  (about  2  per  cent., 
Tliiersch),  and,  during  an  exposure  of  several  weeks,  the  fluid 
should  be  frequently  changed.  It  is  well  to  add  a  little  glycerine. 
The  effect  may  be  increased  by  a  little  hydrochloric  acid,  with- 
out injury  to  delicate  textures.  The  decalcified  specimen,  after 
being  washed,  is  to  be  placed  in  absolute  or  strong  alcohol  for 
further  hardening.  A  similar  decalcifying  effect  may  also  be 
obtained  with  pyroligneous  acid  (see  below). 

Oxalic  Acid.— Oxalic  acid  was  formerly  but  little  or  not  at  all 
used  by  histologists.  Some  time  since  M.  Schultze  instituted  a 


FLUID    MEDIA   AND    CHEMICAL    EEAGENTS.  133 

series  of  experiments  with  it  which  assign  it  a  not  unimportant 
rank  among  the  microscopist's  reagents.  A  cold  saturated  solu- 
tion of  oxalic  acid  (one  part  of  pure  crystalline  hydrated  acid 
requires  for  its  solution  15  parts  of  water)  causes  connective 
tissue  structures  to  swell  and  become  transparent,  while  the  tis- 
sue elements  which  are  formed  of  albuminous  substances  retain 
their  sharp  contours,  become  somewhat  hardened  and  permit  of 
convenient  isolation.  Extremely  delicate  elements  of  the  body, 
such  as  the  rods  of  the  retina  and  the  olfactory  cells,  are  pre- 
served in  it  excellently.  The  length  of  time  is  of  relatively 
slight  importance,  so  that  the  examination  may  be  commenced 
after  a  few  hours  or  several  days. 

According  to  Schultze's  experience,  an  alcoholic  solution  of 
oxalic  acid  acts  more  strongly  than  the  watery,  and  appears  to 
present  certain  advantages  for  many  purposes. 

Finally,  oxalic  acid  is  used  in  carmine  tingeing  in  the  same 
manner  as  acetic  acid,  although  more  circumscribed  in  its  appli- 
cation, of  which  mention  will  be  made  later. 

Acetic  Acid. — The  hydrated  acetic  acid,  thoroughly  pure 
acetic  acid,  acidum  aceticum  glaciale,  should  always  be  used 
when  an  accurate  estimation  is  necessary  (since  the  so  popular 
specification  of  the  specific  weight  affords  no  definite  conclusion 
as  to  the  amount  of  water  present),  and  combined  drop  by  drop, 
or  in  greater  quantity,  with  water. 

Acetic  acid,  which  is  so  rapid  in  its  action,  is  one  of  the  old- 
est and  most  frequently  employed  reagents  in  animal  histology. 
Its  property  of  rendering  nuclei  within  the  cells  visible,  or  of 
causing  them  to  appear  isolated  after  the  destruction  of  the 
envelope  arid  cell  body ;  and  further,  of  giving  to  connective 
tissue  a  crystalline  transparency,  and  disclosing  its  admixture  in 
the  cells,  elastic  fibres,  vessels,  nerves,  etc.,  has  especially  led  to 
its  general  employment. 

Only  at  a  later  period  were  quantitatively  defined  solutions 
of  acetic  acid,  as  well  as  combinations  of  the  same  with  other 
fluids,  especially  alcohol,  employed  for  more  prolonged  action 
on  animal  tissues.  Even  a  few  drops  of  the  acid  to  the  ounce 
of  water  is  sufficient  to  induce  considerable  transparency  of  the 
connective  tissue  in  a  few  days.  In  this  way,  for  example,  the 


134  SECTION    SEVENTH. 

intestinal  ganglia  lying  in  the  submucosa ;  furthermore,  the  mar- 
vellous ganglionic  plexuses,  discovered  years  ago  by  Auerbach, 
between  the  muscular  layers  ;  also  muscle  cells  in  the  mucous 
membranes,  on  vessels,  etc.,  are  made  to  appear  distinctly.  For 
the  recognition  of  smooth  muscles,  Moleschott  used  a  1  or  1£ 
per  cent,  solution  of  acetic  acid  for  a  few  minutes.  One  part 
by  measure  of  strong  acid,  of  1.070  specific  weight,  is  to  be 
mixed  with  99  of  water,  that  is,  1£  to  98J. 

More  recently,  Kolliker  has  used  very  dilute  acetic  acid  for 
rendering  the  muscles  of  the  frog  transparent,  in  order  to  dis- 
cern the  nerve  terminations,  and  the  reagent  accomplishes  this 
exceedingly  well.  He  recommends  the  addition  of  8,  12,  or  16 
drops  of  the  acidurn  aceticum  concentratum  of  the  Bavarian 
pharmacopoeia,  of  1.045  specific  weight,  to  100  cubic  centimetres 
of  water.  I  have  substituted  1  to  2  drops  of  hydrated  acetic 
acid  to  50  cubic  centimetres  of  water.  Acetic  acid  of  from  0.3 
to  0.2  per  cent,  has  been  employed  by  others  for  many  pur- 
poses. 

Acetic  acid,  diluted  to  an  extreme  degree,  is  also  to  be  recom- 
mended for  softening  thin  sections  from  parts  which  have  been 
dried  in  the  air ;  also  for  washing  out  specimens  after  they  have 
been  tinged  in  carmine,  in  order  to  fix  the  red  in  the  nucleus. 
This  will  be  again  alluded  to  further  below. 

Maceration  in  acetic  acid  presents  a  certain  difficulty  in  the 
recognition  of  delicate  structural  relations,  in  so  far  as  that  the 
part  should  be  examined  at  the  right  time.  Before  this  period, 
the  swelling  and  transparency  are  still  too  little  developed;  later, 
however,  the  changes  induced  in  the  tissue  by  the  acid  have 
become  too  considerable. 

Beale  has  recommended  the  combination  of  acetic  acid  with 
glycerine. 

Vinegar. — The  employment  of  ordinary  cooking  vinegar 
offers  no  kind  of  advantage.  In  it  connective  tissue  becomes 
transparent  like  glass,  after  6,  8,  or  12  hours.  If  the  tissue 
becomes  too  soft  to  permit  of  sections  being  made,  this  may 
often  be  remedied  by  placing  it,  supplementarily,  in  a  solution 
of  chromic  acid.  It  will  frequently  be  found  useful  to  boil  in 
vinegar  animal  tissues  which  are  to  be  dried. 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.  135 

Pyroligneous  Acid. — Pyroligneous  acid  (none  but  the  puri- 
fied, or  acidum  pjrolignosum  rectificatum,  should  ever  be  em- 
ployed) has  frequently  been  used  for  rendering  connective  tissue 
structures  transparent,  and  especially  with  a  certain  predilection 
for  pathological  tissues.  It  exerts  a  similar,  though  not  entirely 
the  same*  effect  as  diluted  acetic  acid,  inasmuch  as  it  possesses, 
together  with  the  macerating  action,  a  hardening  effect  (from 
admixture  of  products  of  the  dry  distillation  of  the  wood). 
Diluted  pyroligneous  acid  should  always  be  used  for  macerating, 
if  it  be  desired  to  avoid  marked  textural  changes  of  the  elements 
which  then  become  visible  through  the  connective  tissue.  Pyro- 
ligneous acid,  diluted  according  to  circumstances  with  an  equal, 
double,  or  quadruple  volume  of  water,  is  a  good  accessory  for 
many  structural  conditions ;  for  example,  in  the  recognition  of 
the  corneal  cells  and  their  contents,  the  course  of  the  nerves  in 
the  sub-mucous  connective  tissue,  etc.,  and  especially  structures 
which  are  embedded  in  connective  tissue,  such  as  glandular  ele- 
ments, vessels,  pathological  new  formations,  etc.  The  desired 
effects  generally  take  place  after  one  or  more  days,  often  enough 
again  disappearing,  as  a  result  of  continued  maceration.  Con- 
sequently, without  regarding  the  smell  or  its  injurious  effects  on 
the  blades  of  the  knives,  there  is  an  inconvenience  in  the  employ- 
ment of  our  reagent.  Besides,  pyroligneous  acid  preparations 
do  not  usually  keep  well  when  put  up  in  glycerine.  We  have, 
therefore,  discontinued  the  use  of  this  fluid  for  many  investiga- 
tions. Still,  it  is  useful  for  extracting  the  bone  earths  from  cal- 
cified cartilage  and  from  normal  and  pathological  bone-tissues. 

Osmic  Acid  (hyperosmic  acid). — Within  a  few  years  this  has. 
come  into  frequent  use  through  M.  Schultze  and  others ;  it  is 
readily  reduced  by  several  tissues  and  substances.  It  shares  this 
property  with  several  similarly  applicable  salts  of  the  nobler 
metals,  which  will  also  be  mentioned  hereafter. 

Picric  Acid. — Recommended  in  part  as  a'  means  of  tingeing, 
by  Schwarz  (see  below),  in  part  for  hardening  tissues.  Accord- 
ing to  Ranvier's  experience,  a  concentrated  solution  produces  an 
excellent  consistence,  even  in  24  hours.  Neither  shrinking  nor 
coagulation  of  albumen  occurs,  and  lime  salts  are  extracted  at  the 
same  time.  I  can  only  coincide  in  these  statements. 


136  SECTION    SEVENTH. 

Iodine.— A  solution  of  iodine,  abont  1  part  iodine  (it  is  well 
to  combine  with  it  3  parts  of  iodide  of  potassium)  to  500  of 
water,  may  be  used  for  tingeing  animal  cells.  Nevertheless,  we 
have  better  and  newer  methods  of  tingeing.  A  solution  of 
iodine  serves  the  microscopist  for  the  recognition  of  amylum, 
and,  in  combination  with  sulphuric  acid,  of  amyloid  and  cellu- 
lose. For  this  purpose  a  watery  solution,  which  should  not  be 
too  strong,  is  allowed  to  act  energetically,  and  then  a  drop  of 
concentrated  sulphuric  acid  is  added. 

It  has  already  been  remarked  above  (page  124)  that  iodine 
forms  a  constituent  of  an  important  mixture,  the  so-called  "  jod- 
serum,"  recently  invented  by  Schultze. 

2.)  Among  the  alkalies,  solutions  of  potash,  soda,  and  ammonia 
are  frequently  used.  They  are  of  quite  inestimable  value  for 
the  investigation  of  animal  tissues ;  this  is  especially  true  of  the 
first  two  substances.  There  is  one  disadvantage,  however,  con- 
nected with  the  use  of  alkalies,  namely,  that  objects  which  have 
been  macerated  in  them  can  hardly  be  preserved  permanently. 

Caustic  Potash  (hydrate  of  potassa). — The  melted  form,  the 
kali  causticum  in  baculis  is  used.  As  this  attracts  water  and 
carbonic  acid  from  the  air  with  great  eagerness,  it  and  its  solu- 
tions must  be  kept  in  well-stoppered  bottles. 

The  kali  causticum  in  baculis  of  commerce  contains,  in  addi- 
tion to  carbonic  acid,  a  variable  and  not  inconsiderable  quantity 
of  water,  which  constitutes  an  inconvenience  in  its  application. 

The  strong  solution  of  potash  softens  the  substance  of  many 
elements,  and  induces  in  them  a  condition  which  is  very  favor- 
able to  the  imbibition  of  water,  which  afterwards  penetrates 
very  rapidly,  so  that  the  cells  swell  up,  burst,  etc. 

Manifold  use  has  been  made,  in  the  investigation  of  tissues, 
of  the  resolving  and  destructive  properties  of  potash  solutions. 
The  manner  in  which  potash  solutions  act  varies  entirely  accord- 
ing to  their  strength;  a  subject  to  which  Donders  first  drew 
attention  many  years  ago.  A  saturated,  or  at  least  very  strong 
solution  softens  many  elements,  without  dissolving  or  attacking 
them  very  strongly.  Although  diluted  solutions  produce  this 
effect  more  or  less  rapidly,  they  also  frequently  dissolve  the 
intermediate  connecting  substance,  the  tissue  cement,  and  thus 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.  137 

become  an  extremely  important,  in  many  cases  invaluable 
accessory.  Credit  is  due  to  Moleschott  for  having  more  recently 
recommended  30  to  35  per  cent,  solutions  of  potash  as  excellent 
reagents.  To  make  a  32.5  per  cent,  solution  of  potash  he  uses 
32.5  parts  by  weight  of  kali  causticnm  in  baculis,,  which  is  to  be 
dissolved  in  67.5  parts  by  weight  of  distilled  water.  An  exposure 
of  J  to  £  an  hour  or  more  is  an  extremely  useful  means  of  iso- 
lating muscular  and  nerve  elements,  glandular  passages,  and 
even  ordinary  ciliated  and  olfactory  cells.  Schultze,  who,  to- 
gether with  other  histologists,  has  likewise  made  use  of  potash 
solutions,  employed  for  the  last-mentioned  delicate  cell  forma- 
tions solutions  of  the  strength  of  28,  30,  32,  35,  and  40  per  cent. 
For  other  purposes,  weaker  solutions  of  5  to  10  per  cent,  are 
necessary,  as  will  be  indicated  in  speaking  of  the  individual 
tissues.  Naturally,  in  the  histological  examination,  the  same 
solutions  should  be  employed  as  a  fluid  medium,  and  the  use  of 
water  avoided,  as  otherwise  the  rapidly  dissolving  effect  of 
diluted  solutions  would  take  place. 

Caustic  Soda  (hydrate  of  soda). — The  white  melted  mass  is 
used  for  making  the  solution.  Although  solutions  of  soda  have 
been  used  experimentally,  they  present  no  superiority,  when 
concentrated,  to  those  of  potash.  AVeaker  solutions  are  generally 
necessary,  about  two-thirds  of  the  potash  quantity  (correspon.d- 
ing  to  the  atomic  weight)  being  used. 

Liquor  Ammonia. — The  action  of  ammonia  on  animal  tissues 
is  similar  to  that  of  potash  and  soda.  Ammonia  is  useful  for 
neutralizing  acids  which  have  been  applied  to  a  tissue  ;  also  as 
a  means  of  dissolving  carmine. 

Lime-water. — Kollett  has  recently  made  us  familiar  with 
lime-water,  which  was  previously  but  little  noticed,  as  an  im- 
portant accessory  for  the  investigation  of  connective-tissue 
structures,  and  especially  tendons.  After  remaining  in  it  for 
six  or  eight  days,  a  piece  of  connective  tissue  may  be  readily 
divided  into  its  fibriUse  by  the  use  of  the  needle.  It  is  there- 
fore one  of  the  animal  cement  substances  which  is  here  dis- 
solved. 

Baryta-water.—  The  same  result  may  be  obtained  with  con- 
nective tissue  by  means  of  the  much  more  energetically  acting 


138  SECTION    SEVENTH. 

baryta-water,  in  from  four  to  six  hours,  as  is  afforded  by  lime- 
water  after  several  days'  action.  At  the  same  time,  the  swelling 
is  rather  greater,  and  the  transparency  somewhat  more  consider- 
able. In  both  cases,  before  the  application  the  tissue  is  to  be 
washed  with  distilled  water,  or,  still  better,  with  distilled  water 
to  which  a  minimum  of  acetic  acid  (just  enough  to  neutralize 
it)  has  been  added. 

3.)  Salts. 

Chloride  of  Sodium.— Formerly,  weak  solutions  of  common 
salt  were  commonly  regarded  as  indifferent  media.  Accord- 
ing to  Graham's  observations,  a  colloid  substance  (albumen 
or  gum-arabic)  should  always  be  added.  A  special  applica- 
tion of  the  chloride  of  sodium  is  also  made  in  the  impregna- 
tion of  tissues  with  nitrate  of  silver,  which  will  be  alluded  to 
hereafter.  It  is  likewise  an  ingredient  of  various  preservative 
fluids. 

Chloride  of  Calciiim. — Chloride  of  calcium  in  solutions  of 
medium  strength  (one  part  of  dry  chloride  of  calcium  to  two  or 
three  parts  of  water)  has  been  recommended  as  a  fluid  medium 
for  microscopic  preparations,  in  consequence  of  its  well-known 
property  of  attracting  water.  It  has  also  been  recommended 
for  rendering  sections  of  the  spinal  cord,  etc.,  transparent,  for 
which  purpose  it  is  not  very  serviceable.  It  has  a  peculiar 
effect  on  muscles. 

Acetate  of  Potash,  in  a  nearly  concentrated  watery  solution, 
has  recently  been  recommended  by  M.  Schultze  as  an  excellent 
preserving  medium. 

Chlorate  of  Potash. — This  is  only  used  in  combination  with 
nitric  acid  (see  this),  as  Schultze's  reagent.  Extremely  varying 
degree's  of  concentration  of  this  mixture  have  been  made  use  of 
in  animal  histology,  and  the  desired  effect  has  naturally  been 
obtained  in  very  unequal  spaces  of  time. 

Phosphate  of  Soda. — Solutions  of  phosphate  of  soda  of  5 
to  10  per  cent,  have  been  considerably  used  by  microscopists. 
According  to  my  experience  thus  far,  they  do  not  present  any 
advantages. 

Bichromate  of  Potash  (Bed  Chromate  of  Potash).— The 
purest  possible  crystallized  material  should  be  used.  The  action 


FLUID    MEDIA   AND    CHEMICAL    REAGENTS.  139 

of  this  salt,  which  may  be  very  suitably  combined  with  glycerine, 
is  similar  to  that  of  chromic  acid,  but  weaker,  and  not  so  rapid 
in  its  appearance.  For  hardening  many  tissues  it  is  extremely 
serviceable,  and  perhaps  it  is  better  than  the  free  adulterated 
acid  ;  it  also  exerts  a  much  less  coagulating  effect  on  albumen. 
Besides  this,  the  solutions  of  this  salt  have  the  advantage  of  not 
readily  developing  mould,  which  is  a  great  fault  of  chromic 
acid  solutions.  It  has  also  been  recommended  to  commence 
the  hardening  process  with  our  salt,  and  then  to  continue  it 
with  the  free  acid  (Deiters). 

Where  one  part  of  chromic  acid  would  be  sufficient,  it  is  re- 
quisite to  have  several  parts  of  chromate  of  potash.  Thus, 
where  a  given  effect  might  be  obtained  with  a  fluid  containing 
from  •}•  to  £  of  a  grain  of  free  chromic  acid,  to  accomplish  the 
same  without  the  acid,  the  fluid  would  require  from  1  to  4 
grains  of  the  salt.  However,  for  delicate  investigations,  much 
less  depends  on  the  accurate  concentration  of  the  solutions  of 
chromate  of  potash  than  of  the  chromic  acid. 

A  mixture  of  the  salt  in  question  with  sulphate  of  soda  has 
been  recommended  by  H.  Miiller  for  hardening  the  retina. 
The  tissue  should  be  exposed  to  its  action  for  at  least  two  weeks. 
Bichromate  of  potash,  2 — 2£  grammes. 

Sulphate  of  soda,  1          " 

Distilled  water,  100          " 

This  mixture,  the  "  Muller's  eye-fluid,"  is  also  very  useful  for 
preserving  many  other  tissues,  such  as  mucous  membranes, 
glands,  and  even  ciliated  cells.  It  preserves  delicate  embryos 
exquisitely,  and  may  naturally  be  modified  according  to  neces- 
sity. 

Bichromate  of  Ammonia. — This  has  been  recommended  by 
Gerlach  in  the  place  of  the  previous  salt,  in  solutions  of  1  or  2 
per  cent.,  for  hardening  the  central  organs  of  the  nervous 
system. 

Molyldate  of  Ammonia. — This  was  recently  recommended 
by  Krause  as  an  indifferent  medium  for  tingeing. 

Chloride  of  Iron. — This  iron  salt  was  formerly  used  by 
Fiihrer  and  Billroth  for  hardening  the  spleen,  which  becomes 
sufficiently  hardened  in  from  1  to  2  hours  in  a  solution  of  the 


140  SECTION    SEVENTH. 

color  of  Madeira  or  Malaga  wine.  Chloride  of  iron  is  at  present 
supplanted  by  superior  hardening  media. 

Chloride  of  Mercury. — The  chemical  effects  of  the  sublimate 
are  well  known.  Macerating  for  several  days  in  a  solution  of 
this  salt  may  be  advantageously  used  for  hardening  and  isolating 
the  axis  cylinders.  Although  this  reagent  has  found  but  little 
application,  still  it  forms  an  element  of  several  very  serviceable 
preservative  fluids. 

Nitrate  of  Silver. — This  has  recently  come  into  use  for  a  pe- 
culiar tingeing  process  of  the  tissues,  especially  through  His  and 
Recklinghausen  (see  below). 

Chloride  of  Gold. — This  was  advantageously  employed  for  a 
similar  purpose  by  Cohnheim,  Kolliker,  Eberth,  Gerlach,  and 
many  others. 

Chloride  of  Gold  and  Calamine. — This  has  been  employed 
by  Gerlach. 

Chloride  of  Palladium  was  first  used  by  F.  E.  Schulze. 

Chloride  of  Platinum. — As  Merkel  informs  us,  this  salt 
hardens  tissues  and  gives  them,  at  the  same  time,  a  diffuse  yel- 
low tinge,  especially  those  of  flattened  organs.  Equal  portions 
of  solutions  of  chromic  acid  and  chloride  of  platinum  (each 
1  :  400)  are  recommended  for  the  connective-tissue  frame-work 
of  the  retina. 

4.)  Alcohol. — Alcohol,  the  most  common  of  the  preservative 
fluids  for  animal  tissues,  is  of  inestimable  value  for  histological 
investigations.  The  use  of  alcohol  has  come  more  into  the 
foreground  chiefly  within  a  few  years,  since  we  have  learned  to 
recognize  in  glycerine  an  incomparable  means  of  rendering 
transparent  animal  tissues  which  have  been  hardened  and  hence 
become  cloudy.  It  is  only  for  certain  purposes  that  chromic 
acid  deserves  the  preference.  Either  small  pieces  of  the  en- 
tirely fresh  organ  are  placed  in  a  relatively  considerable  quan- 
tity of  alcohol  free  from  water,  or  several  sorts  of  alcohol  are 
employed.  Weak  alcohol  is  used  for  the  first  few  days ;  this  is 
then  replaced  by  stronger,  and  perhaps,  later,  a  still  stronger 
one  is  employed.  I  know  of  no  better  reagent  for  hardening 
glandular  organs,  the  digestive  canal,  or  injected  preparations, 
and  for  rendering  them  fit  for  sections  and  brushing.  Lat- 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.  141 

terly,  entire  series  of  investigations  have  thus  been  made  almost 
exclusively  with  alcoholic  preparations.  The  circumstance  that 
the  specimens  do  not  spoil  in  well-closed  vessels  constitutes  an 
advantage  over  chromic  acid,  which  so  readily  develops  the 
formation  of  fungi.  The  latter  is,  on  the  contrary,  preferable 
to  alcohol  for  the  recognition  of  many  of  the  finest  structural 
conditions,  for  the  central  organs  of  the  nervous  system  and  for 
the  organs  of  sense. 

Alcohol  is  also  frequently  applicable  in  other  ways.  First 
of  all,  for  microscopic  objects  which  are  to  be  deprived  of  their 
water  with  the  utmost  possible  sparing  of  the  texture,  for  the 
purpose  of  being  afterwards  mounted  in  Canada  balsam  or 
similar  resinous  masses.  In  such  cases  the  thin  sections  are  to 
be  placed  for  one  or  two  days  in  absolute  alcohol.  From  this 
they  go  into  oil  of  turpentine. 

Furthermore,  alcohol  forms  an  ingredient  of  Beale's  cold  in- 
jecting fluid,  which  will  also  be  alluded  to  further  on. 

Finally,  alcohol  is  also  an  ingredient  of  several  recently  re- 
commended mixtures,  the  description  of  which  follows : — 

L.   CLARKE  AND  BEALE'S  MIXTURES. 

These  serve  to  make  delicate  parts  hard  and  at  the  same  time 
clear.  The  fundamental  idea  consists  in  employing  two  sorts 
of  substances,  one  of  which  hardens  the  albuminous  elements 
of  the  tissues,  while  the  other  renders  them  transparent.  Beale, 
who  has  occupied  himself  considerably  with  the  action  of  these 
solutions,  remarks  that  they  must  be  varied  according  to  ne- 
cessity, also  that  by  the  addition  of  glycerine  to  the  mixture  its 
refractive  power  may  be  increased  according  to  circumstances. 
He  recommends  in  general  alcohol,  glycerine,  acetic  acid,  hydro- 
chloric acid,  potash,  and  soda.  The  last  two  acids  as  well  as 
alcohol  coagulate  albuminous  matters  ;  acetic  acid,  potash,  and 
soda  render  them  transparent ;  alcohol  dissolves  fat.  When 
several  of  these  materials  are  combined  in  a  solution,  the  above 
mentioned  effects  are  obtained. 

(a.)  Alcohol  and  Acetic  Acid. — L.  Clarke  used  in  his  inves- 
tigations a  mixture  of  acetic  acid  and  alcohol,  which,  as  I  have 


142  SECTION   SEVENTH. 

also  convinced  myself,  renders  sections  of  the  spinal  cord  mar- 
vellously clear,  even  in  a  few  hours,  and  permits  many  things 
to  be  better  recognized  than  by  other  methods  customary  for 
this  purpose.  Lenhossek  also  appears  to  have  made  use  of  this 
process  in  his  investigations  on  the  spinal  cord. 

Clarke's  recipe,  naturally  to  be  modified  according  to  ne- 
cessity, is  to  combine  three  parts  of  alcohol  with  one  part  of 
acetic  acid. 

(1.)  Moleschotfs  mixture  of  Acetic  Acid  and  Alcohol. — Mo- 
leschott  recommends  the  following  modification  of  Clarke's 
method : — 

Strong  acetic  acid  (1.070  sp.  wt.) 1  volume. 

Alcohol  (0.815  sp.  wt.) 1       " 

Distilled  water 2       " 

He  calls  this  his  strong  acetic  acid  mixture.  This  fluid  is  very 
serviceable  for  hardening  many  organs,  causes  the  connective- 
tissue  portions  to  become  transparent,  and  renders  those  formed 
of  albuminous  matters  distinctly  prominent.  Delicate  textures 
do  not,  as  a  rule,  tolerate  it  so  well.  Another  weaker  acetic 
acid  mixture  was  afterwards  recommended,  consisting  of 

Acetic  acid  (same  as  above) 1  volume. 

Alcohol 25       " 

Distilled  water 50       " 

(c.)  Alcohol,  Acetic  Acid,  and  Nitric  Acid. — Beale  recom- 
mends the  addition  of  a  little  nitric  acid  to  the  mixture  of  alco- 
hol and  acetic  acid  for  the  examination  of  epithelial  structures. 
This  is  also  to  be  varied  as  necessity  may  require.  A  recipe 
given  by  the  author  runs  as  follows  : — 

"Water 1  ounce. 

Glycerine 1      " 

Spirit 2      " 

Acetic  acid 2  drachms. 

Hydrochloric  acid !  drachm. 

Alcohol  and  Soda. — Beale  obtained  excellent  results,  in  many 
investigations,  from  the  use  of  a  fluid  composed  of  alcohol  and 
a  solution  of  caustic  soda,  in  the  proportion  of  from  eight  to  ten 
drops  to  each  ounce  of  alcohol.  Many  tissues  are,  at  the  same 
time,  rendered  very  hard  and  transparent  in  such  a  mixture,  and 


FLUID    MEDIA    AND    CHEMICAL    REAGENTS.  143 

it  is  particularly  adapted,  according  to  his  experience,  for  inves- 
tigations upon  the  character  of  calcareous  matter  deposited  in 
tissues  in  various  morbid  processes,  also  in  tracing  the  stages  of 
ossification  in  the  early  embryo.  It  renders  all  the  soft  tissues 
perfectly  transparent,  but  exerts  no  action  on  the  earthy  matter 
of  bone.  The  most  minute  ossific  points  can  therefore  be  very 
readily  discovered.  A  foetus,  for  example,  prepared  by  being 
soaked  for  a  few  days  in  this  fluid,  and  preserved  in  weak 
spirit,  forms  a  very  beautiful  preparation.  This  fluid  will  also 
be  found  very  useful  in  investigations  upon  soft  granular  or- 
gans. Beale  found  it  of  special  service  when  working  at  the 
anatomy  of  the  liver. 

Methyl  Alcohol. — In  England,  where  the  high  spirit  duty  im- 
poses an  obstacle  to  the  employment  of  the  ordinary  (ethyl) 
alcohol,  methyl  alcohol  (pyro-acetic  spirit)  is  frequently  used  as 
a  substitute  ;  this  is  however  unnecessary  on  ^he  Continent. 
Methyl  alcohol  has  found  special  application  as  an  addition  to 
Beale's  cold  injection  fluid  (see  below),  and  also  in  mounting 
microscopic  specimens  in  Canada  balsam. 

Sections  which  have  been  deprived  of  their  water  by  means 
of  absolute  alcohol  are  placed  for  a  short  time  in  strong  methyl 
alcohol,  then  taken  out  of  this  and,  just  as  they  are  commenc- 
ing to  dry,  thrown  into  oil  of  turpentine.  The  latter  penetrates 
sections  which  have  been  in  methyl  alcohol,  as  I  have  learned 
by  experience,  somewhat  more  readily  than  those  which  are 
brought  from  the  absolute  alcohol  directly  into  this  oil.  Never- 
theless, methyl  alcohol  may  be  readily  dispensed  with  for  this 
purpose. 

Chloroform. — Thus  far  it  has  been  very  little  used  for  his- 
tological  investigations,  but  forms  the  best  medium  for  dissolv- 
ing and  thinning  the  Canada  balsam,  which  is  so  important  for 
practical  microscopy. 

JEther. — This  serves  to  dissolve  fat  in  microscopic  work.  It 
also  dissolves  Canada  balsam. 

Collodium. — So  far,  this  has  only  been  used  for  recognizing 
the  axis  cylinder  of  nerve  fibres.  According  to  the  statements 
of  Pfluger  and  my  own  observations,  it  acts  instantaneously. 

Oil  of  Turpentine. — This  comes  next  to  chloroform  as  a 


144  SECTION    SEVENTH. 

medium  for  thinning  Canada  balsam.  It  also  forms  the  most 
important  medium  for  rendering  transparant  dried  sections,  or 
those  which  have  been  deprived  of  their  water  by  absolute 
alcohol.  We  will  return  to  this  subject  more  in  detail  further 
below. 

Creosote.  —  Creosote  forms  an  element  of  preservative 
mounting  fluids  (Harting). 

It  has  recently  been  recommended  by  Stieda,  after  the  ex- 
ample of  Kutschin,  as  a  very  rapidly  acting  medium  for  render- 
ing microscopic  sections  transparent.  The  property  which 
creosote  has  of  rapidly  making  preparations  which  still  contain 
water  transparent,  is  of  great  importance.  By  this  means, 
objects  which  have  lain  in  ordinary  spirits,  and  even  chromic 
acid,  can  be  used  after  a  few  minutes.  But  when  a  prepara- 
tion is  to  be  arranged  for  mounting  in  Canada  balsam,  good 
oil  of  turpentine  deserves  the  preference,  decidedly,  according 
to  our  experience. 

Oil  of  Cloves. — This  was  first  made  known  by  Rindfleisch, 
as  a  medium  for  rendering  tissues  transparent,  in  the  place  of 
the  oil  of  turpentine ;  it  has  also  been  warmly  recommended 
by  others.  It  renders  tissues  which  contain  water  transparent 
in  the  same  manner  as  creosote,  but  more  slowly.  A  series  of 
other  ethereal  oils,  such  as  cinnamon,  anise,  bergamot,  and 
rosmarine  oils,  act  similarly  to  it,  while  others,  like  oil  of 
turpentine,  render  only  objects  which  have  been  deprived  of 
their  water  transparent ;  as  orange,  juniper,  mentha  crispa, 
citron,  and  cajeput  oils  (Stieda). 

Benzine. — This  has  been  proposed  for  dissolving  and  thinning 
Canada  balsam  in  the  place  of  chloroform  and  oil  of  turpen- 
tine (Bastian).  Toldt  recently  recommended  pure  benzine  as 
an  excellent  medium  for  making  fat  tissue  transparent,  after 
the  previous  momentary  action  of  alcohol. 

In  what  has  been  mentioned  above,  we  have  been  obliged  to 
adhere  to  the  methods  which  are  still  generally  used  by  micro- 
scopists  for  determining  the  proportions  of  their  reagents. 
Titrition  is  a  far  more  certain  and  a  much  more  convenient 
method  for  ascertaining  the  strength  of  a  solution,  and  for  pro- 
ducing them  of  definite  proportions. 


FLUID    MEDIA    AND    CHEMICAL    EEAGENTS. 


145 


In  order  to  estimate  the  acid  and  alkaline  contents  of  such 
fluids  the  following  is  necessary : — 

The  apparatus  (fig.  74),  which  is  quite  indispensable  for  the 


Fig.  74.  Apparatus  for  titrition.  1,  a  Mohr's  burette,  with  the  clamp  at  a,  which  is  opened  by 
pressing  on  the  two  metallic  buttons  at  ft,  allowing  the  fluid  to  escape  from  the  tube  c  ;  2,  a  pipette  ; 
3,  a  cylindrical  measure. 

investigation,  consists  of :  — a)  two  Monies  burettes  (1)  of  about 
60  ccm.  capacity  divided  into  ^  of  a  ccm. ;  #)  a  pipette  (2) 
which  will  allow  from  10  to  15  ccm.  to  run  out,  and  is  divided 
into  ^  of  a  ccm.,  and  finally  c)  a  cylindrical  measure  (3)  of 
100  or  several  hundred  ccm.  capacity.  The  divisions  of  the 
latter  are  from  5-5,  or  10-10  ccm.,  and  must  retain  the  desig- 
nated quantity  of  fluid,  and  not  allow  it  to  flow  out ;  while  the 
10 


146  SECTION   SEVENTH. 

burette  and  pipette  are  so  divided  as  only  to  designate  the 
number  of  ccm.  which  they  allow  to  flow  or  drop  out.  (Such 
burettes,  pipettes.,  and  cylindrical  measures  may  now  be  pur- 
chased everywhere). 

The  use  of  the  pipette  is  self-evident.  As  to  the  burette,  it 
is  filled  to  the  zero  division  at  its  upper  part  with  the  reagent 
(the  test  acid  or  the  test  alkali),  and,  by  making  slight  pressure 
on  the  clamp,  the  fluid  is  allowed  to  flow  out  either  in  a  stream 
or  by  single  drops,  as  may  be  necessary. 

The  normal  acid  and  normal  alkali  solutions  are  used  for  the 
construction  of  the  test  fluids,  so  far  as  determining  the  ordinary 
reagents  (acids  and  alkalies)  is  concerned.  Under  these  are 
understood  solutions  which  contain  an  equivalent  weight  of  the 
active  substance  of  the  reagent,  expressed  in  grammes,  dissolved 
in  1000  ccm.  (1  litre)  of  fluid. 

1.  The  Normal  Oxalic  Acid  Solution. — In  its  formation  6.4 
grammes  of  pure  crystallized,  uneffloresced  oxalic  acid  is  to  be 
dissolved  in  water,  and  this  solution  diluted  sufficiently  to  make 
100  ccm.  of  fluid.     (The  volume  is  always  to  be  measured  at 
the  same  temperature  at  which  the  solution  is  to  be  used,  there- 
fore at  14  to  16  R.)     This  normal  oxalic  acid  solution  is,  how- 
ever, only  indirectly  employed,  that  is,  in  the  preparation  of 
other  normal  acid  and  normal  alkali  solutions.     For  this  reason 
the  greatest  accuracy  and  care  should  be  employed  in  the  pre- 
paration of  this  first  and  most  important  solution. 

One  ccm.  of  this  oxalic  acid  solution  contains,  as  we  are 
already  aware,  0.064  grm.  of  oxalic  acid.  For  its  saturation  the 
corresponding  equivalent  of  bases  is  necessary,  therefore  of— 

a.  Soda 0.031    grm.  NaO. 

1.  Potash 0.0472     "     KO. 

c.  Ammonia 0.017       "     NII3. 

d.  Lime 0.028       "     CaO. 

e.  Baryta 0.0765     "     BaO. 

2.  Normal  Potash  Solution. — From  a  freshly  prepared  so- 
lution of  potash,  free  from  carbonic  acid,  take,  with  a  pipette, 
5  ccm.,  color  it  to  a  weak  blue  with  a  few  drops  of  tincture  of 
lacmus,  and,  while  stirring,  allow  the  normal  oxalic  acid  solu- 
tion to  flow  into  it  from  the  burette  till  the  color  begins  to  turn 


FLUID    MEDIA    AND    CHEMICAL    EE  AGENTS.  147 

red.  Given,  we  had  used  8  ccm.  of  normal  acid  solution ;  we 
then  add  to  each  5  ccm.  of  our  potash  solution,  3  ccm.  of  water. 
In  this  case  we  have  a  normal  potash  solution ;  1  ccm.  of  the 
same  is  just  sufficient  to  saturate  1  ccm.  of  the  oxalic  acid  solu- 
tion ;  it  therefore  contains  the  above-mentioned  quantity  of 
potash,  or  0.0472  grm. 

It  is  clear  that  with  the  aid  of  this  potash  solution  the  quan- 
tity of  acid  present  in  any  fluid  may  be  determined  at  pleasure. 
By  the  neutralization  of  1  ccm.  of  our  normal  potash  solution  is 
indicated  the  presence  of — 

a.  Sulphuric  acid  ==  0.04      grm.  SO8. 

I.  Nitric  "     =  0.054      "     NO6. 

c.  Muriatic      "     =  0.0365     "     HC1. 

d.  Acetic          «     =  0.06        "     CJI4O4. 

"We  limit  ourselves  in  this  citation  to  the  investigation  of  the 
most  important  acids. 

3.  As  actually  pure  oxalic  acid  belongs  to  the  more  expen- 
sive reagents,  it  is  unnecessary  to  use  just  this  acid  in  the  esti- 
mation of  alkalies.  Sulphuric  acid  is  generally  used.  Nothing 
is  easier  than  the  preparation  of  the  normal  sulphuric  acid  solu- 
tion. Sulphuric  acid,  diluted  at  pleasure,  is  allowed  to  flow 
from  a  burette  into  5  ccm.  of  normal  potash  solution,  to  which 
several  drops  of  tincture  of  litmus  has  been  added,  till  it  be- 
comes red.  The  acid  and  alkali  solutions  are  then  to  be  diluted, 
corresponding  to  what  was  mentioned  above  concerning  potash, 
until  an  equal  number  of  ccm.  of  each  exactly  neutralize  each 
other.  Accordingly,  1  ccm.  of  this  normal  sulphuric  acid  con- 
tains 0.04  grm.  of  SO3,  and  for  its  neutralization  exactly  the 
same  quantities  of  the  bases  are  necessary  as  were  previously 
given  for  oxalic  acid. 

Finally,  we  add  two  other  teet  fluids,  namely: — 1.  The  nor- 
mal silver  solution  for  the  quantitative  estimation  of  common 
salt.  One  ccm.  of  the  -fa  normal  solution  contains  0.0108  Ag., 
or  0.0170  AgONO6.  It  corresponds  to  0.00585  NaCl.  2.  The 
normal  chloride  of  sodium  solution,  used  for  the  quantitative 
estimation  of  nitrate  of  silver.  One  ccm.  of  the  ^  normal  so- 
lution contains  0.00585  NaCl.  and  corresponds  to  0.0170 
AgONO6.  In  both  cases  a  precipitate  of  chloride  of  silver 


148  SECTION    SEVENTH. 

takes  place,  which  collects  in  lumps  by  strong  shaking ;  the 
operation  is  completed  when  a  drop  of  the  test  fluid  no  longer 
induces  precipitation.  To  make  the  recognition  more  certain 
in  the  first  of  the  two  processes,  several  drops  of  simple  chro- 
mate  of  potash  solution  may  be  added  to  the  common  salt  solu- 
tion, in  which  case  the  complete  precipitation  of  the  chloride  of 
silver  will  be  indicated  by  the  red  color  of  the  chromate  of  sil- 
ver which  is  formed. 

A  few  examples  may  serve  to  make  the  method  of  employ- 
ment clear. 

1.  We  have  10  ccm.  of  a  solution  of  soda,  which  required 
22.2  ccm.  of  normal  sulphuric  acid  for  its  neutralization.     Now 
1  ccm.  of  the  normal  sulphuric  acid  corresponds  to  0.031  grm. 
!N"aO.     By  multiplication    with    22.2    the    quantity  of    soda 
contained  in  10  ccm.  of  the  titrated  fluid  will  be  found  to 
be    0.6882,   consequently  6.882    per  cent,   (disregarding    the 
specific  weight). 

2.  A  solution  of  ammonia  requires  for  10  ccm.  12.6  ccm. 
normal  sulphuric  acid.     One  ccm.  normal  sulphuric  acid  cor- 
responds to  0.017  HN3.     The  quantity  of  ammonia  is,  there- 
fore, 2.142  per  cent. 

3.  5  ccm.  of  acetic  acid  solution  requires  41.7  ccm.  of  the 
normal  potash  solution,  10  would  therefore  require  double  this 
quantity,  or  83.4.     But  the  cubic  centimetre  of  normal  potash 
solution  corresponds  to  0.06  of  acetic  acid,  and  hence  the  pro- 
portion of  acetic  acid  is  50.04  per  cent. 

4.  10   ccm.   of    a   solution   of    common   salt    requires,   for 
example,  12  ccm.  of  the  ^  normal  silver  solution.     "Now  as 
1    ccm.    of    the    ^    normal    silver    solution   corresponds  to 
0.00585  NaCl.,  the  common  salt  solution  contains  0.702  per 
cent,  of  NaCl. 

5.  10  ccm.  of  a  solution  of  nitrate  of  silver  requires  15.5  ccm. 
of  the  Y1^  normal  chloride  of  sodium  solution.     But  1  ccm.  of 
the  -fa  common  salt  solution  corresponds  to  0.017  AgONOB, 
and  the  silver  solution  contains  2.635  per  cent,  of  AgONO6. 

6.  Supposing  we  desire  to  construct  a  40  per  cent,  solution 
of  acetic  acid  from  the  diluted  acetic  acid  mentioned  in  No.  3. 
We  learn  from  the  proportion   40  :  100=50.04:    x,  that  we 


FLUID   MEDIA   AND    CHEMICAL    KEAGEOTS.  149 

have  to  dilute  100  ccm.  of  the  acetic  acid  solution,  which  has 
been  estimated  by  titrition,  to  125.1  ccm. 

7.  Let  us  suppose  the  case,  that  we  wish  to  prepare  a  soda 
solution  of  20  per  cent.,  and  that  a  solution  which  we  have 
titrated  showed  a  proportion  of  37.5  per  cent,  of  NaO.    "We 
find  by  calculation  that  100  ccm.  of  the  latter  solution  is  to  be 
diluted  to  187.5  ccm. 

8.  "We  wish  to  make  a  1  per  cent,  solution  of  nitrate  of  silver. 
For  this  purpose  we  use  the  2.635  per  cent,  solution  of  nitrate 
of  silver  of  No.  5.     It  requires  diluting  with  water  to  263.5 
ccm. 


Qtttwn 


METHODS  OF  STAINING— IMPREGNATION"  WITH  METALS— THE 
DRYING  AND  FREEZING  PROCESSES. 

I.    METHODS  OF  STAINING. 

DELICATE  animal  tissues  frequently  gain  an  extraordinary  dis- 
tinctness when  impregnated  with  indifferent  coloring  materials, 
and  complicated  structures  are  frequently  essentially  cleared  up 
in  the  same  way.  The  non-reception  of  the  color  by  other 
tissue  elements  is  also  of  great  value  for  assisting  our  discrimi- 
nation in  certain  cases.  These  staining  processes,  therefore, 
form  a  very  important  accessory  for  histological  investigations, 
and  science  is  greatly  indebted  to  Professor  Gerlach,  the  inven- 
tor of  carmine  tingeing. 

1.   GerlaoKs  method  of  tingeing  with  carmine. 

Gerlach  first  gave  us  this  process  in  a  small  work  ("  Hikrosko- 
pische  Studien  aus  dem  Gebiete  der  menschlichen  Morphologie." 
Erlangen),  which  appeared  in  the  year  1858.  In  his  carmine 
injections  he  had  already  noticed  the  eagerness  with  which  the 
nuclear  structures  of  the  blood-vessels  absorbed  the  carminate  of 
ammonia,  and  how  differently  they  behaved  in  this  respect  to 
the  cells  and  intercellular  substance.  The  cells  also  absorb 
coloring  matter,  but  much  more  slowly  and  with  greater  diffi- 
culty, and  always  in  lesser  quantity  than  the  nuclear  formations. 
Intercellular  substances  act  nearly  indifferently. 

Gerlach's  first  experiments  were  made  on  the  brain  and  spinal 
cord.  Fine  sections  of  organs  previously  hardened  in  chromate 
of  potash  were  placed  in  a  moderately  concentrated  solution  of 
the  carminate  of  ammonia  and  left  in  it  for  10  or  15  minutes. 
He  then  soaked  them  for  several  hours  in  water,  which  was  fre- 
quently renewed,  then  treated  them  with  acetic  acid  and  placed 


METHODS    OF    STAIKOTG.  151 

them  in  absolute  alcohol  to  remove  the  water.  The  carmine 
solution  tinges  even  when  it  is  still  more  diluted.  Gerlach  ob- 
served this  at  the  very  first,  having  one  night  left  a  section  of  a 
convolution  of  the  cerebellum  lying  in  some  water  slightly  con- 
taminated with  carmine.  In  this  case  things  showed  themselves 
which  were  not  to  be  recognized  by  the  first  method  of  staining. 
Thereupon  Gerlach  employed  2  or  3  drops  of  a  concentrated 
solution  of  ammonia  carmine  to  the  ounce  of  water,  leaving  his 
sections  in  it  from  2  to  4  days.  This  is  the  purport  of  the  first 
statement  of  the  inventor. 

Since  that  time  carmine  tingeing  has  come  into  the  most  fre- 
quent use.  Several  years  ago  one  observer  went  so  far  as  to 
assume  the  presence  in  the  central  organs  of  several  kinds  of 
nerve  cells,  to  which  he  assigned  different  functions  according 
to  their  capacity  for  absorbing  carmine. 

The  directions  for  its  use  have  been  more  or  less  fortunate. 
From  what  my  own  experience  has  taught,  two  evils  are  to  be 
especially  avoided  in  carmine  staining  ;  one  is  an  excessive  tinge- 
ing,  ultimately  inducing  a  very  deep  and  diffuse  red,  which  does 
not  permit  of  further  recognition  of  the  preparation ;  the  other 
is  an  infiltration  of  the  elements  of  the  tissue  in  consequence  of 
the  action  of  the  ammonia. 

Solutions  as  free  as  possible  from  ammonia  should  therefore 
be  used.  For  this  purpose  take  several  grains  of  carmine,  com- 
bine it  with  an  ounce  of  distilled  water  and  a  few  drops  of  am- 
monia. The  fluid,  in  which  a  portion  of  the  carmine  has 
become  dissolved,  is  to  be  filtered.  Another  portion  of  the  car- 
mine, which  remains  on  the  filter,  may  be  kept  for  future  use. 
When  the  filtrate  has  any  appreciable  smell  of  ammonia,  the 
latter  should  be  allowed  to  escape  by  leaving  it  in  an  open  ves- 
sel under  a  bell-glass  for  a  half  or  a  whole  day.  If,  after  a 
time,  granules  of  carmine  are  deposited,  a  drop  of  liquor  am- 
monia serves  to  redissolve  them.  However,  all  solutions  of 
carmine  are  very  decomposable  and  their  coloring  power,  unfor- 
tunately, very  unequal — an  inconvenience  which  cannot  be 
entirely  obviated. 

The  fluid  thus  obtained  is,  when  used  for  tingeing,  to  be  added, 
drop  by  drop,  to  water,  in  order  to  obtain  at  pleasure  a  lighter 


152  SECTION   EIGHTH. 

or  more  intensive  red.  For  very  delicate  objects  a  combination 
of  the  coloring  water  with  an  equal  quantity  of  glycerine  is 
advantageous. 

I  recommend  for  this  purpose  three  to  six  grains  of  carmine 
dissolved  in  exactly  the  necessary  quantity  of  ammonia  and 
mixed  with  one  ounce  of  distilled  water.  To  the  filtered  fluid, 
one  ounce  of  good  glycerine  and  two  or  three  drachms  of  strong 
alcohol  are  to  be  added.  The  solution  is  to  be  used  either  as  it 
is  or  with  a  further  addition  of  glycerine. 

The  length  of  time  which  it  is  necessary  for  a  portion  of  tis- 
sue to  remain  in  the  fluid  is  determined  by  the  intensity  of  the 
color  of  the  latter.  Strong  solutions  tinge  sufficiently  in  a  few 
minutes,  weaker  ones  require  several  hours.  The  preparations 
may  be  left  without  disadvantage  for  twenty-four  hours  in  very 
weak  solutions. 

The  stained  pieces,  when  taken  out,  are  first  washed  with 
pure  water.  They  are  then  exposed  for  several  minutes  to  a 
solution  of  acetic  acid.  I  employ,  as  a  rule,  an  ounce  of  dis- 
tilled water  with  two  or  three  drops  of  glacial  acid  ;  although  a 
much  stronger  acid  may  be  used  for  a  much  longer  time  without 
harm.  The  process  may  be  readily  modified  where  it  is  desira- 
ble to  avoid  the  further  infiltration  of  the  tissue  with  water. 
The  stained  object  may  be  deprived  of  its  water  with  absolute 
alcohol,  and  then  exposed  to  the  glacial  acid  from  one  to  twenty- 
four  hours  (Thiersch),  or  an  acidulated  alcohol  may  be  directly 
applied.  This  may  also  be  accomplished,  as  Beale  correctly 
remarks,  with  glycerine  containing  glacial  acetic  acid  (five 
drops  to  the  ounce).  Only  with  tissues  of  very  unequal  capacity 
for  swelling,  a  saturated  watery  solution  of  oxalic  acid  deserves 
the  preference  to  acetic  acid  (Thiersch).  Nevertheless,  it  finally 
extracts  the  red  from  the  nucleus,  and  the  color  is  less  intensive. 
Fresh  tissues,  or  those  hardened  in  alcohol,  color  best ;  not  so 
good,  and  somewhat  more  slowly,  those  which  have  been  hard- 
ened in  chromic  acid  or  chromate  of  potash.  Good  carmine 
preparations  show  the  nuclei  intensively  reddened,  likewise  the 
axis  cylinder  of  the  nerve  fibres.  The  coloring  of  the  proto- 
plasma  is  usually  less  lively ;  the  connective  tissue  interstitial 
substance  appears  colorless,  etc. 


METHODS    OF    STAINING.  153 

One  soon  learns  to  properly  estimate  the  intensity  of  the  color 
of  the  tissue.  In  general,  the  preparations  destined  for  wet 
mounting  (in  weakly  acidulated  glycerine)  are  to  be  less  deeply 
tinged  than  those  for  resinous  mounting.  The  latter  (best 
mounted  cold  in  Canada  balsam  dissolved  in  chloroform)  often 
furnish  charming  preparations  for  review. 

Injected  specimens  are  very  susceptible  of  tingeing  with  many 
colors,  such  as  chrome  yellow  and  sulphate  of  baryta.  The  best 
kinds  of  soluble  Prussian  blue  are  also  useful  for  staining; 
although  a  somewhat  more  strongly  acidulated  washing- water  is 
necessary  to  retain  the  lively  blue.  It  is  more  appropriate  for 
objects  injected  with  carmine  to  stain  them  blue  or  violet ;  never- 
theless very  handsome  appearances  may  also  be  obtained  with 
a  very  light  red  carmine. 

The  employment  of  ordinary  red  ink,  of  which  use  has  here 
and  there  been  made,  is  to  be  little  recommended. 

2.  Thiersctts  Carmine  Fluid. 

Professor  Thiersch  employs  several  methods  of  staining. 
a.  Red  Fluid. 

Carmine 1  part. 

Caustic  ammonia 1     " 

Distilled  water 3     " 

This  solution  is  to  be  filtered. 

A  second  solution  is  to  be  prepared  of — 

Oxalic  acid 1  part. 

Distilled  water 22     " 

One  part  of  the  carmine  solution  is  to  be  mixed  with  8  parts 
of  the  oxalic  acid  solution,  and  12  parts  of  absolute  alcohol  are 
to  be  added,  and  filtered. 

If  the  filtrate  is  orange-colored  instead  of  dark-red,  more 
ammonia  is  added  to  compensate  for  the  preponderance  of  oxalic 
acid,  and  the  orange  becomes  red.  The  orange  color  may  also  be 
used  for  staining.  If  crystals  of  oxalate  of  ammonia  are  after- 
wards formed  in  the  solution,  which  may  take  place  from  the 
addition  of  liquor  ammonia  or  alcohol,  it  must  be  filtered  a 
second  time. 

According  to  Thiersch's  experience,  this  solution  stains  tis- 


154  SECTION   EIGHTH. 

sues  very  uniformly  in  the  short  space  of  from  1  to  3  minutes, 
without  causing  them  to  swell  and  without  loosening  shreds  of 
epithelium.  After  the  staining,  the  coloring  material  adhering 
to  the  surface  of  the  preparation  is  to  be  washed  off  with  alco- 
hol of  about  80  per  cent.  "When  the  color  has  become  too  dark 
or  diffuse,  the  preparation  is  to  be  washed  out  with  an  alcoholic 
solution  of  oxalic  acid. 

b.  Lilac  Carmine  Fluid. 

Borax 4  parts. 

Distilled  water 56      " 

Dissolve  and  add,  of  carmine 1      " 

The  red  solution  is  to  be  mixed  with  twice  its  volume  of 
absolute  alcohol,  and  filtered.  Carmine  and  borax  remain  on 
the  filter  5  this  precipitate,  dissolved  in  water,  may  be  again 
used. 

Thiersch  found  that  this  solution  colored  more  slowly  than 
the  simple  red  one,  and  that  it  was  especially  attracted  by  car- 
tilage and  by  bones  which  have  been  decalcified  by  chromic 
acid.  Alcoholic  solutions  of  oxalic  and  boracic  acids  serve  for 
washing.  Preparations  may  be  very  beautifully  stained  by 
tingeing  them  in  the  lilac  solution  and  then  placing  them  for 
an  instant  in  the  red  fluid. 

3.  Bealds  Carmine  Fluid. 

This  meritorious  investigator  has  recommended  the  following 
mixture : — 

Carmine 10  grains. 

Strong  liquor  ammonia ^  drachm. 

Good  glycerine 2  ounces. 

Distilled  water 2       " 

Alcohol \  ounce. 

The  pulverized  carmine  is  to  be  placed  in  a  test  tube  and  the 
ammonia  added  to  it.  By  agitation,  and  with  the  aid  of  heat, 
the  carmine  is  soon  dissolved.  The  ammoiiiacal  solution  is  to 
be  boiled  for  a  few  seconds  and  then  allowed  to  cool.  After 
the  lapse  of  an  hour,  much  of  the  excess  of  ammonia  will  have 
escaped.  The  glycerine,  water,  and  alcohol  may  then  be  added 
and  the  whole  passed  through  a  filter  or  allowed  to  stand  for 


METHODS    OF    STAINING.  155 

some  time,  and  the  perfectly  clear  supernatant  fluid  poured  off 
and  kept  for  use.  Yarious  tissues  require  very  unequal  time 
for  staining. 

Heidenhain's  process  (first  used  for  the  mucous  membrane  of 
the  stomach)  is  a  modification  of  Beale's  method.  The  solution 
is  to  be  prepared  without  the  alcohol,  and  the  superfluous 
ammonia  almost  entirely  removed  by  warming  on  the  water- 
bath,  or  the  addition  of  acetic  acid.  (The  proportion  of  ammo- 
nia is  proper  when,  after  24  hours,  all  the  carmine  of  a  solution 
remaining  in  a  small  open  dish  has  become  deposited  in  gran- 
ules.) The  specimen  is  to  be  placed  in  a  watch-glass  with  this 
nearly  free  from  ammonia  solution.  This  watch-glass,  and 
another  containing  water  and  a  trace  of  ammonia,  are  to  be 
placed  in  a  flat  glass  vessel  which  can  be  accurately  closed  and 
left  for  24  hours.  Afterwards  washed  in  glycerine,  and  then 
placed  in  pure  glycerine,  the  preparations  are  to  be  exposed  in 
the  same  manner  to  the  vapor  of  a  small  quantity  of  acetic 
acid.  Such  a  protective  method  of  staining  certainly  presents 
manifold  advantages.  Modifications  of  the  same  may  also  be 
readily  made. 

4.  Add  Carmine  Fluid. 

Schweigger  Seidel  recommends  the  following  method  for 
tingeing  objects  previously  treated  with  acids: — An  ordinary 
ammoniacal  solution  of  carmine  is  to  be  mixed  with  acetic  acid 
in  excess  and  filtered.  The  red  solution  thus  obtained  stains 
diffusely;  but  after  the  addition  of  glycerine,  tempered  with 
a  little  muriatic  acid  (1 :  200),  to  the  microscopic  preparation, 
the  cell  body  is  seen  to  gradually  lose  its  color,  and  the 
carmine  is  only  retained  by  the  nucleus.  For  mounting  in 
glycerine,  the  preparation  is  to  be  washed  with  water  containing 
acetic  acid. 

5.  Staining  with  Anilin  red  (Fuchsiri). 

The  idea  of  employing  the  anilin  colors,  so  much  used 
at  present,  for  tingeing  animal  tissues  was  very  natural. 
A  series  of  experiments  which  I  had  undertaken  for  this 


156  SECTION   EIGHTH. 

purpose  showed  the  pre-eminent  usefulness   of  this  coloring 
material. 

Fuchsin  (crystallized) 1  centigramme. 

Absolute  alcohol 20-25  drops. 

Distilled  water 15  cubic  centimetres. 

A  beautiful  moderately  intense  red  color  results.  It  colors 
many  of  the  animal  tissues  almost  instantly,  and  without 
altering  them.  It  is  especially  adapted  for  the  study  of 
epithelium,  hyaloid  membranes,  the  lens  and  corpus  vitreum. 
Diluted  with  a  little  water,  this  solution  tinges  the  vibrating 
cilia  of  the  ciliated  epithelium  of  the  frog,  without  causing 
the  motion  to  cease.  The  colored  blood  cells  also  become 
stained,  although  slowly.  The  same  solution  of  f  uchsin  is  also 
useful  for  coloring  the  ganglion  cells  and  the  cellular  elements 
of  lymphatic  glands ;  but  it  appears  to  me  to  be  not  so  well 
adapted  for  cartilage  and  bones.  The  nerve  tubes,  after  an 
immersion  of  several  hours,  become  slightly  red,  and  their  axis 
cylinders  become  sensibly  darker. 

The  above  examples  show  that  the  solution  produces  effects 
which  are  superior  in  many  respects  to  those  obtained  with 
carmine.  The  promptitude  and  uniformity  of  the  coloration 
are  qualities  which  render  the  fuchsin  solution  especially  valu- 
able as  a  staining  medium  for  instantaneous  demonstrations, 
and  for  coloring  pale  delicate  cells,  which  thus  become  more 
distinct  without  suffering  alteration.  It  is  very  unfortunate 
that  alcohol  soon  extracts  the  color,  so  that  it  is  impossible  to 
preserve  the  preparations  in  Canada  balsam.* 

6.  Blue  Colors  for  Staining. 

It  is  desirable  in  many  cases  to  make  use  of  a  blue  fluid, 
especially  for  staining  specimens  injected  with  carmine.  Other 
preparations  also  appear  very  beautiful  when  stained  with  this 
fluid,  so  that  for  many  purposes  I  am  inclined  to  give  it  the 
preference  to  carmine.  Several  of  these  methods  are  now  prac- 
tised, as  with  the  sulph-indigate  of  potash  (so-called  indigo  car- 
mine), with  anilin  blue,  and  soluble  parme. 

*The  nitrate  of  roseanilin  (Magenta  red)  in  watery  solution  has  been 
recommended  by  Roberts  and  Abbey. 


METHODS    OF    STAINING.  157 

a.  Blue  Staining  with  Indigo  Carmine. 

The  following  solution  has  been  recommended  by  Professor 
Thiersch : — 

Oxalic  acid 1  part. 

Distilled  water 22—30  parts. 

Indigo  carmine,  as  much  as  the  solution  will  take  up. 

The  soda  salt  also  affords  an  excellent  blue  fluid.  If  the  blue 
color  is  in  excess  it  may  be  removed  with  a  solution  of  oxalic 
acid  in  alcohol. 

This  blue  fluid  (which  may  also  be  diluted  at  pleasure  with 
alcohol),  when  concentrated,  tinges  very  rapidly  and  uniformly. 
According  to  the  observation  of  its  inventor,  it  is  very  suitable 
for  coloring  the  axis  cylinders  and  nerve  cells  of  the  brain  and 
spinal  cord,  previously  hardened  in  chromic  acid. 

"b.  Anilin  Blue  Fluid. 

Ordinary  anilin  blue  is  insoluble  in  water.     By  treating  it 
with  sulphuric  acid,  the  soluble  blue  may  be  obtained.     This 
may  be  simply  dissolved  in  water  until  it  assumes  a  deep  cobalt 
color,  or  the  following  solution  may  be  prepared  : — 
Soluble  anilin  blue. ...  2  centigrammes. 

Distilled  water 25  cubic  centimetres. 

Alcohol 20—25  drops. 

This  fluid  stains  tissues  preserved  in  alcohol  of  a  lively  blue, 
and  in  a  few  minutes,  but  those  preserved  in  chromic  acid  are 
not  colored  so  rapidly.  This  color  may  be  preserved  in  water, 
alcohol,  and  glycerine,  and  is  not  altered  by  the  addition  of 
acids.  The  lymphatic  glands,  spleen,  walls  of  the  intestines, 
and  more  particularly  sections  of  the  brain  and  spinal  cord  as- 
sume, under  its  influence,  a  fine  appearance.  I  have  made  very 
extended  use  of  it  for  years  and  can  recommend  it  thoroughly. 

This  method  of  staining  has  recently  been  improved  by  Hei- 
denhain. 

He  employs  the  neutral  reacting  aqueous  solution  in  still 
higher  dilution,  so  that,  when  poured  into  a  watch-glass,  it  shows 
on  a  light  ground  a  forget-me-not  blue  color.  The  sections 
(from  alcoholic  preparations)  remain  for  a  day  in  4  ccm.  of  this 


158  SECTION   EIGHTH. 

fluid  in  a  moist  place,  and  are  then  to  be  immediately  mounted 
in  glycerine  and  cemented.  The  color  and  coloring  power  of 
the  solution  are  considerably  increased  by  the  addition  of  a  little 
acetic  acid,  or  even  its  vapor ;  the  vapor  of  ammonia,  on  the 
contrary,  deprives  it  of  its  color  entirely. 

c.  /Soluble  Parme  Fluid. 

This  substance,  which  is  obtained  by  treating  diphenylate  of 
roseanilin  with  sulphuric  acid,  when  dissolved  in  water  in 
about  the  proportion  of  1 : 1000,  gives  a  gorgeous  blue,  running 
into  violet,  and  colors  the  various  tissues  in  a  few  minutes. 
They  are  then  to  be  washed  in  water,  and  either  examined  in 
glycerine  or,  after  being  deprived  of  their  water  by  absolute 
alcohol,  are  to  be  mounted  in  Canada  balsam. 

7.   Violet  Tingeing  with  JTcematoxylin. 

Boehmer  has  brought  to  our  knowledge  a  valuable  coloring 
medium  in  hsematoxylin.  lie  dissolves  20  grains  of  the  same 
in  half  an  ounce  of  absolute  alcohol,  and  prepares  a  solution  of 
alum  of  2  grains  to  the  ounce  of  water.  A  watch-glass  is 
filled  with  the  latter,  and  by  the  addition  of  two  or  three  drops 
of  the  solution  of  hsematoxylin  a  violet  color  is  obtained,  which 
should  act  on  the  preparation  for  a  half  or  a  whole  day.  I 
have  also  obtained  the  same  result  in  a  more  simple  way.  An 
aqueous  solution  of  the  extract  of  logwood  is  to  be  mixed  with 
a  solution  of  alum  (1  part  of  the  salt  to  8  parts  of  water)  till 
the  deep  impure  red  color  has  become  violet,  and  then  filtered. 

Hardened  preparations  (alcoholic  or  chromic  acid)  are  to  be 
placed  in  it  for  about  half  an  hour,  fresh  sections  requiring  a 
longer  time,  and  then  washed  in  water  or  alcohol.  Most  tissues 
are  colored  very  beautifully  and  evenly,  and  objects  injected 
with  carmine  or  Prussian  blue  afford  very  good  preparations 
with  it,  and  may  be  permanently  mounted  in  Canada  balsam. 

8.  Blue  Tingeing  with  MolyMate  of  Ammonia. 

Krause  has  recommended  this  salt  in  a  neutral  solution  of  5 
per  cent,  as  an  indifferent  medium  for  giving  a  marine  blue 
color  to  various  tissues,  as  those  of  the  nervous  apparatus, 


METHODS    OF    STAINING.  159 

lymphatic  glands,  and  ciliated  epithelial  cells.  The  staining  is 
completed  in  24  hours,  at  an  ordinary  temperature  and  under 
the  action  of  light.  The  preparations  become  brown,  and 
assume  a  consistence  suitable  for  making  sections,  by  supple- 
mentary exposure  to  the  action  of  tannic  acid  (1  :  1.5)  or  pyro- 
gallic  acid  (20  per  cent). 

9.  Double  Staining  with  Carmine  and  Picric  Acid. 

To  the  methods  of  staining  previously  known,  a  new  one  haa 
been  added,  by  E.  Schwarz,  for  double  tingeing.  lie  combines 
staining  with  carmine  with  that  by  picric  acid. 

That  author  places  the  tissues  in  a  mixture  consisting  of  1 
part  creosote,  10  parts  acetic  acid,  and  20  parts  water.  The 
preparations  are  to  be  immersed  in  this  mixture,  while  it  is 
boiling,  for  about  a  minute,  and  are  then  to  be  dried  (for  two  or 
three  days).  Thin  sections  are  to  be  made  and  immersed  for  an 
hour  in  water  slightly  acidulated  with  acetic  acid,  and  then 
washed  out  in  distilled  water.  Next  they  are  to  be  put  in  an 
extremely  dilute  watery  solution  of  ammoniacal  carmine,  and, 
after  being  again  washed  in  water,  are  exposed  for  two  hours  to 
a  solution  of  picric  acid  (O.OCG  grm.  to  400  ccm.  water).  The 
sections  are  then  placed  on  a  slide,  the  superfluous  acid  is 
allowed  to  flow  away,  and  a  mixture  of  4  parts  of  creosote 
to  1  part  of  turpentine,  which  has  become  resinous  from 
age,  is  dropped  on  to  it.  In  about  half  an  hour  the  speci- 
men, which  has  become  transparent,  is  to  be  mounted  in  Canada 
balsam. 

If  it  is  undesirable  to  use  the  creasote  mixture,  the  sections 
are  to  be  removed  from  the  watery  picric  acid  solution  to  an 
alcoholic  mixture  of  corresponding  strength,  in  order  to  deprive 
them  of  their  water. 

A  peculiar  effect  is  thus  obtained.  Epithelial  and  glandular 
cells,  muscles,  and  the  walls  of  vessels  show  a  yellowish  color 
with  reddened  nuclei,  while  the  connective  tissue  is  not  colored 
by  the  picric  acid,  and  only  presents  the  carmine  color. 

These  preparations  are  very  handsome,  and  the  method  pro- 
mises to  be  of  importance,  especially  for  the  demonstration  of 
muscular  elements. 


160  SECTION   EIGHTH. 

10.  Pier o- Carmine  Staining. 

Ranvier,  a  meritorious  investigator,  is  the  inventor  of  this 
method  of  staining.  A  saturated  solution  of  picric  acid  is  to  be 
prepared  and  filtered,  and  to  this  a  strong  ammoniacal  solution 
of  carmine  is  to  be  added,  drop  by  drop,  till  neutralization  takes 
place.  Slight  precipitations,  caused  by  commencing  over-acidu- 
lation,  may  be  removed  by  filtration  (Flemming). 

11.  METALLIC  IMPREGNATIONS. 

Within  a  few  years  histological  investigation  has  gained 
important  accessories  in  several  readily  reducible  combinations 
of  the  noble  metals.  Aqueous  solutions  of  nitrate  of  silver, 
osmic  acid,  chloride  of  gold  and  of  palladium,  have  thus  far 
come  into  use.  Their  effects  are  essentially  different,  so  that  we 
shall  have  to  discuss  each  solution  by  itself. 

a.  Nitrate  of  Silver. 

Lapis  inf ernalis,  in  solution  or  in  substance,  has  been  used  for 
a  number  of  years  for  obtaining  precipitates  of  silver  in  the 
cornea.  This  method  was  first  extensively  used  by  Reckling- 
hausen  ("  Die  Lymphgefasse,"  Berlin,  1862)  on  animal  tissues. 
His  then  endeavored  to  ascertain  the  nature  and  conditions  of 
the  precipitates.  A  great  number  of  observers  have  lately  made 
good  and  bad  use  of  the  process. 

Only  fresh  (or  but  slightly  altered)  tissues,  which  are  still 
saturated  with  the  albuminous  organic  fluids,  are  suitable  for 
impregnation  with  silver.  As  the  action  of  nitrate  of  silver  is, 
for  the  most  part,  confined  to  the  surface,  they  should  be  chiefly 
thin,  membranous  structures.  Artificial  surfaces,  made  by  the 
knife,  generally  produce  only  very  unsatisfactory  results. 

It  is  preferable  to  employ  only  very  weak  solutions,  those  of 
0.5, 0.25,  and  0.2  per  cent.,  or  still  weaker,  according  to  circum- 
stances. Frequently  the  immersion  lasts  for  only  the  fraction 
of  a  minute,  till  the  fragment  of  tissue  is  seen  to  assume  a  whit- 
ish color.  It  is  then  to  be  washed  in  water  and  exposed  to  the 
light  until  a  brownish  color  is  noticed.  The  examination  may 


METALLIC    IMPREGNATIONS.  161 

be  made  in  acidulated  water  or  glycerine.     Tingeing  with  car- 
mine may  also  be  advantageously  combined  with  this  process. 

To  increase  its  durability,  Legros  recommends  the  immersion 
of  the  colored  object  in  a  solution  of  hyposulphite  of  soda  for 
an  instant ;  it  is  then  to  be  washed  in  distilled  water.  Silver 
preparations  which  have  become  too  dark  may  be  brightened 
up  again  by  a  prolonged  action  of  this  salt. 

Although  the  silver  method  produces  excellent  specimens  in 
many  cases,  there  are  a  number  of  defects  connected  with  it  be- 
sides those  which  have  been  mentioned.  One  of  these  is  that 
the  nuclear  structures  very  soon  become  indistinct,  and  later 
disappear  entirely.  Then,  with  every  precaution,  the  desired 
result  is  not  always  obtained,  and  the  appearances  which  the 
strongly  acting  nitrate  of  silver  produces  are  frequently  very  dis- 
similar, and  are  often  so  heterogeneous  that  the  observer  remains 
completely  confused  by  them.  The  greatest  foresight  in  the  in- 
terpretation of  such  artificial  productions  is  therefore  necessary 
— and  this,  unfortunately,  has  been  frequently  neglected. 

The  silver  treatment  gives  decidedly  the  best  results  with 
epithelium,  especially  with  unstratified  pavement  cells,  and  the 
membranes  and  tubes  covered  by  them.  Here  we  have  pro- 
duced a  mosaic,  consisting  of  sometimes  finer,  sometimes  broader, 
dark  lines  of  demarcation,  which  enables  us  to  recognize  the 
contours  of  the  cells  most  distinctly.  This  results  either  from 
blackening  of  the  cement  substance,  or  from  the  formation  of 
the  dark  precipitate  of  silver  in  the  narrow  furrows  between 
the  cells.  Such  appearances  are  in  no  wise  liable  to  misinter- 
pretation so  soon  as  the  nuclei  can  be  recognized  or  the  scales 
isolated.  We  shall  afterwards  see  to  what  beautiful  discoveries 
in  the  structure  of  the  finest  blood  and  lymph  passages  this 
method  has  led. 

However,  even  in  this  case,  instead  of  the  bright  field  surround- 
ed by  dark  lines,  we  sometimes  have  a  diffuse,  brownish  darken- 
ing of  the  scales,  without  the  black  lines  of  demarcation., 

The  outlines  of  smooth  muscle  cells  are  also  made  visible  in 
a  beautiful  manner  by  this  reagent.     How  far  it  may  serve  for 
demonstrating  the  finer  structural  relations  of  nerve  tissue, 
f  uture  investigations  will  have  to  decide. 
11 


162  SECTION   EIGHTH. 

Opinions  have  thus  far  agreed  quite  as  little  with  regard  to 
the  importance  of  the  nitrate  of  silver  solution  for  connective 
tissue  and  relative  structures ;  on  the  contrary,  the  views  of 
observers  are  very  widely  separated  on  this  point. 

According  to  Recklinghausen's  statements,  a  diffuse  colora- 
tion of  the  basis  substance  takes  place,  from  which  the  cavities 
and  cells  glimmer  forth  in  the  form  of  bright  spaces.  Exactly 
the  reverse  may  also  take  place,  a  dark,  granular  precipitate  of 
silver  being  formed  in  them,  while  the  interstitial  substance 
remains  bright.  It  has  been  recommended  to  use  a  solution  of 
common  salt  to  obtain  the  latter  appearance  (His). 

We  are  inclined  not  to  advise  the  silver  method  for  connect- 
ive tissue. 

1.  Osmic  Acid  (Ilyperosmic  Acid). 

"  The  treatment  of  animal  tissues  with  solutions  of  osmic  acid 
(OsO4),  introduced  by  M.  Schultze,*  permits  of  a  very  manifold 
application.  Organic  substances  reduce  the  acids  from  their 
solutions,  and  hence  a  combination  of  the  former  with  a  lower 
grade  of  oxidation,  or  perhaps  with  metallic  osmium  results, 
which  combination,  sooner  or  later,  and  independent  of  light, 
assumes  a  dark  bluish  black  color,  and  resists  decomposition. 
The  reduction  does  not  follow  in  the  tissue  as  a  granular  pre- 
cipitate ;  on  the  contrary,  the  elementary  structures,  if  fresh 
when  immersed  in  it,  retain  the  same  transparency  and  texture 
which  they  have  in  life,  and  are  only  altered  so  far  as  color  is 
concerned.  These  changes  of  color  take  place  in  different  tis- 
sues with  very  different  degrees  of  rapidity,  and  on  this  is  based 
an  important  advantage  of  the  method.  Evidently  this  condi- 
tion is  due  to  a  difference  in  the  reducing  power,  or  to  the 
relation  of  the  organic  substances  to  the  reduced  lower  grade 
of  oxidation.  Through  this  peculiarity,  osmic  acid  may  render 
structural  relations  visible,  which  could  in  no  other  way  be  so 
summarily  demonstrated.  This  is  the  case  with  the  terminal 
tracheal  cells  in  the  luminous  organ  of  the  Lampyris.  All 
kinds  of  fat  cells  and  fat  drops,  and  the  medullary  matter  of 

*  I  am  indebted  for  this  notice  to  the  kindness  of  my  highly  respected  col- 
league in  Bonn. 


METALLIC   IMPREGNATIONS.  163 

central  and  peripheral  nerves  become  rapidly  colored  black; 
more  slowly,  the  substance  of  the  ganglion  cells  and  of  the  axis 
cylinders,  the  muscular  fibres,  and  all  highly  albuminous  ele- 
ments, such  as  cells  rich  in  protoplasm  a,  red  blood  corpuscles, 
and  the  fibres  of  the  lens.  The  intercellular  substance  of  con- 
nective tissues  which  afford  gelatine  and  mucus,  cellulose,  amy- 
lum,  the  watery  intercellular  fluid  of  many  vegetable  cells, 
which  only  contain  traces  of  dissolved  organic  substances,  color 
most  slowly  of  all  (M.  Schultze  and  Rudneff).  The  chief  value 
of  the  method  depends  on  the  property  of  osmic  acid  of  pre- 
serving the  most  delicate,  perishable  tissues,  which  are  most 
sensitive  to  reagents,  in  a  condition  apparently  the  same  as  in 
life  ;  as,  for  example,  embryonic  tissues,  the  cells  of  connective 
tissue,  the  central  organs  and  peripheral  portions  of  the  nervous 
system,  the  retina,  etc.  In  this  respect  osmic  acid  excels  all  pre- 
viously known  reagents,  as,  properly  applied,  it  prevents  all  gran- 
ular coagulation,  and  does  not  allow  even  the  structural  changes 
which  result  from  spontaneous  post-mortem  coagulation  to  take 
place.  It  is  preferable  to  make  use  of  pretty  strong,  that  is, 
from  one  to  two  per  cent.,  watery  solutions.  It  is  best  to  allow 
the  tissues  to  remain  in  this  solution  but  a  short  time,  from  a 
quarter  of  an  hour  to  twenty-four  hours.  If  allowed  to  act  for 
several  hours  or  days,  the  piece  becomes  quite  hard  and  of  a 
very  dark  color.  As  the  solution  does  not  penetrate  very 
deeply,  very  small  pieces  should  be  selected  for  immersion. 
Weaker,  -fa  per  cent,  solutions,  which  do  not  harden  the  tissues 
so  much,  may  also  be  advantageously  used.  The  exhalations 
from  osmic  acid  are  injurious  to  the  respiratory  organs  and  the 
conjunctiva,  and  are  therefore  to  be  carefully  avoided." 

c.  Osmiamide. 

Owsjannikow  recommends  Fremy's  osmiamide  (1  :  1000), 
that  is,  the  amide  combination  of  osmious  acid  OsO3,  which  is 
OsOglljN,  as  a  substitute  for  the  disagreeable  volatile  acid. 

d.   Chloride  of  Gold. 

The  action  of  the  chloride  of  gold,  which  Cohnheim  intro- 
duced into  histology,  is  much  slower  and  less  energetic  than 


164  SECTIOK   EIGHTH. 

that  of  a  solution  of  nitrate  of  silver,  so  that  a  prolonged  im- 
mersion of  the  (freshest  possible)  tissue  is  necessary,  whereby 
the  quantity  of  the  fluid  appears  to  make  comparatively  little 
difference.  A  0.5  per  cent,  solution  of  the  gold  salt  is  to  be 
used  ;  it  is  preferable  to  temper  it  with  a  minimal  quantity  of 
acetic  acid.  Leave  the  specimen  in  the  solution  from  15  or  20 
minutes  to  an  hour  or  more,  till  the  former  assumes  a  distinct 
straw  color,  which  here,  in  contradistinction  to  nitrate  of  silver, 
penetrates  deeply.  After  washing  the  preparation  in  ordinary 
or  distilled  water,  place  it  for  24  to  48  hours  or  more  in  acidu- 
lated water,  leaving  the  vessel  exposed  to  the  light.  If  the 
reduction  has  taken  place,  the  color  varies ;  in  the  best  cases  it 
is  a  beautiful  intense  red,  sometimes  violet  blue  or  a  deep  gray. 
They  afterwards  grow  darker,  assuming  even  a  black  tone  of 
color. 

According  to  Cohnheim's  experience,  the  chloride  of  gold 
does  not  act  on  cornified  cells  and  those  having  no  protoplasma, 
like  simple  flattened  epithelium  and  the  scales  of  epidermis 
(nor  on  their  so-called  cementing  substance) ;  furthermore,  it 
does  not  act  on  the  interstitial  substance  of  connective  tissue 
and  cartilage.  Finally,  it  exerts  no  effect  on  the  cell  nucleus  ; 
still  this  is  well  preserved,  the  action  of  the  gold  impregnation 
being  in  general  much  milder  and  much  less  alterative  than 
that  of  the  silver  impregnation.  On  the  contrary,  the  chloride 
of  gold  is  energetically  and  with  relative  rapidity  reduced  by 
the  protoplasma  of  the  cell,  such  as  that  of  the  lymphoid  and 
glandular  cells  and  the  cellular  elements  of  the  connective 
tissue  and  cartilage ;  further,  by  the  capillary  vessels  and  the 
muscles.  The  chloride  of  gold  reduces  most  energetically — and 
herein  the  chief  value  of  this  new  method  appears  to  lie — the 
elements  of  the  nervous  system,  the  ganglia,  the  medullary 
sheaths  of  the  nerves,  which  assume  a  dark,  almost  blue  red 
color,  and  the  axis  cylinder,  which  assumes  a  brighter,  more 
lively  red  color. 

According  to  what  has  just  been  mentioned,  the  impregna- 
tion with  gold  promised  to  be  of  the  greatest  importance  for 
the  finer  anatomy  o$  the  nervous  system,  the  originator  of  the 
method  having  also  succeeded  in  making  a  beautiful  discovery 


METALLIC   IMPREGNATIONS.  165 

in  the  corneal  nerves.  Unfortunately,  the  method  soon  proved 
to  be  almost  capriciously  uncertain,  in  many  cases  leaving  one 
entirely  in  the  lurch,  while  other  observers  again  obtained 
favorable  results.  Many  have  made  use  of  solutions  as  weak 
as  0.005  per  cent.  Immersion  in  a  solution  of  sulphate  of 
oxide  of  iron  is  said  to  induce  rapid  reduction  (Nathusius). 

[Dr.  Francis  Delafield  recommends  that  the  tissue  be  dipped 
for  a  moment  in  water  containing  a  minimal  quantity  of  acetic 
acid,  before  exposing  it  to  the  gold  solution — a  procedure 
which  I  find  to  improve  the  results  materially.] 

e.  Chloride  of  Gold  and  Potassium. 

This  was  first  used  by  Gerlach,  several  years  ago,  in  solutions 
of  0.01  per  cent.,  for  sections  of  the  spinal  cord  which  had  beea 
hardened  in  the  bichromate  of  ammonia.  It  was  afterwards 
used  by  Arnold,  likewise  extremely  diluted,  for  the  fresh  sym- 
pathetic of  the  frog.  We  shall  again  refer  in  a  more  extended 
manner  to  this  method. 

f.  Protochloride  of  Palladium  (Chloride  of  Palladium). 

A  few  years  ago,  F.  E.  Schulze  made  us  acquainted  with  the 
action  of  this  salt.  In  order  to  dissolve  the  dry  salt  in  distilled 
water,  it  is  necessary  to  add  a  slight  quantity  of  muriatic  acid. 
He  employs  a  solution  of  0.1  per  cent.  (1 : 800 — 1 : 1500).  From 
a  half  to  a  whole  ounce  of  this  fluid  (of  a  wine-yellow  appear- 
ance) hardens  a  piece  of  tissue  of  the  size  of  a  bean,  in  the 
course  of  two  or  three  days,  to  a  consistence  proper  for  cutting, 
and  at  the  same  time  colors  it.  According  to  the  experience  of 
the  discoverers,  chloride  of  palladium  is  especially  adapted  for 
the  recognition  of  striated  and  smooth  muscles,  which  thereby 
become  brownish  and  straw-colored.  Cells  rich  in  protoplasma 
(epidermis  and  glands)  likewise  assume  a  yellow  color.  Corni- 
fied,  fat,  and  connective  tissues  do  not  become  colored.  Fur- 
thermore, the  medullary  matter  of  the  nerves  assumes  a  black 
color,  by  direct  action.  Schulze  also  praises  this  reagent  for 
the  retina  and  crystalline  lenses ;  like  the  chloride  of  gold,  it 
causes  the  nuclear  formations  to  appear  sharply,  and  by  subse- 
quently tingeing  the  connective  tissue  with  carmine,  very  in- 


166  SECTION   EIGHTH. 

structive  preparations  are  afforded.  It  is  an  unpleasant  cir- 
cumstance that  with  many  tissues,  as  the  brain  and  epidermis, 
the  action  remains  quite  superficial. 

The  preparations  are  to  be  carefully  washed  and  mounted  in 
glycerine. 

g.  Prussian  Blue. 

•  Leber  recommends  a  peculiar  method  of  impregnation,  more 
especially,  however,  for  the  cornea  of  the  frog.  The  fresh  or- 
gan is  to  be  immersed  for  several  minutes  in  a  0.5-1  per  cent, 
solution  of  a  protoxide  salt  of  iron.  It  is  then  to  be  taken  out 
for  the  removal  of  its  epithelium,  after  which  it  is  to  be  replaced 
in  the  fluid  for  a  short  time,  so  that  the  total  action  amounts  to 
about  five  minutes.  After  washing  the  cornea  with  water,  it  is 
to  be  seized  with  the  forceps  and  moved  to  and  fro  for  a  few 
moments  in  a  1  per  cent,  solution  of  ferrocyanide  of  potassium 
till  the  preparation  assumes  an  intense  and  uniform  blue  color. 
Finally,  after  again  washing  the  specimen  in  water,  it  shows  a 
colored  basis  substance,  while  the  corneal  cells  and  canals  have 
remained  transparent.  The  color  penetrates  very  deeply,  and 
subsequent  tingeing  with  iodine,  carmine,  and  f  uchsine  readily 
succeeds.  This  method  promises  to  be  useful. 

III.     THE  BUYING  METHOD. 

We  also  add  to  the  methods  above  mentioned,  that  of  drying 
animal  tissues.  The  object  of  this  process  is  to  give  the  parts 
such  a  degree  of  hardness  and  firmness,  by  depriving  them  of 
their  water,  that  the  thinnest  sections  may  be  obtained  by  the 
aid  of  a  sharp  knife,  which  again  swell  up  by  the  addition  of 
water,  and  thus  resume  their  natural  appearance.  We  have 
already,  in  a  previous  section,  become  acquainted  with  a  series 
of  chemical  reagents,  such  as  chromic  acid,  chromate  of  potash, 
and  alcohol,  which  are  used  for  the  same  purpose. 

The  drying  process  is  decidedly  better  adapted  for  many 
tissues  and  parts  of  the  body,  as  it  does  not  render  them 
opaque.  Especially  compact  structures,  organs  rich  in  con- 
nective tissue,  as  the  skin,  the  tendons,  and  the  walls  of  vessels, 
also  the  lungs  (even  injected  preparations  of  the  same),  muscles, 


THE   DRYING    METHOD.  167 

epidermis,  crystalline  lens,  and  the  umbilical  cord  may  be  treated 
in  this  manner  with  the  greatest  advantage.  The  drying  process 
is  less  suitable  for  glands,  lymphatic  glands,  and  delicate 
mucous  membranes.  It  is  unserviceable  for  the  brain,  spinal 
cord,  the  nerves,  and  their  terminal  expansions  in  the  higher 
organs  of  sense,  in  consequence  of  their  extreme  softness  and 
instability. 

The  management  of  the  parts  is  very  simple.  They  may  be 
dried  on  a  board  or  a  piece  of  cork,  to  which,  in  certain  cases, 
a  convex  surface  may  be  given.  To  avoid  wrinkling,  many 
textures  may  be  advantageously  stretched  out  and  fastened  to 
the  board  or  cork  with  pins.  The  temperature  should  not  be 
too  low,  as  decomposition  might  take  place  ;  but  considerable 
elevation  of  temperature  is  to  be  avoided  on  account  of  the 
coagulation  of  the  albumen.  A  temperature  of  30  or  40°  C. 
is  most  suitable.  The  sun  of  a  warm  day  may  also  be  very 
well  employed  for  this  purpose.  If  it  be  desired  to  avoid 
warmth,  the  sulphuric  acid  or  the  chloride  of  calcium  apparatus 
of  the  chemical  laboratories  may  be  used. 

The  pieces  selected  for  drying  should  not  be  too  large  and 
the  drying  should  not  be  overdone,  as  they  may  become  so 
brittle  as  to  prevent  one  from  obtaining  fine  sections,  in  conse- 
quence of  the  cracks  and  flaws  which  occur.  Now  and  then 
it  will  be  found  most  suitable  to  have  a  piece  not  entirely 
dried,  having  the  consistency  of  wax.  Naturally  the  blade  of 
the  knife  should  be  dry.  If  the  preparation  is  on  cork,  this 
may  be  used  as  a  support  in  cutting,  hard  wood  being  inju- 
rious to  the  knife. 

The  thin  sections  which  are  made  are  to  be  softened  in  pure 
water,  or  in  water  to  which  a  little  acetic  acid  has  been  added. 
If  they  are  to  be  stained,  they  may  be  placed  directly  into  the 
ammoniacal  solution  of  carmine.  It  is  less  convenient  to 
soften  the  sections  on  the  slide  than  in  a  watch-glass  or  a 
glass  box.  This  process  requires  a  few  minutes'  time,  in  order  to 
allow  the  air  vesicles  to  escape  from  the  spaces  of  the  tissue. 

Dried  pieces  kept  in  a  box,  with  the  addition  of  a  piece  of 
camphor,  constitute  excellent  material  for  many  histological 
demonstrations. 


168  SECTION   EIGHTH. 


IY.     THE  FREEZING  METHOD. 

This  process,  which  has  been  made  use  of  more  recently,  also 
affords  good  results,  and  in  a  much  more  conservative  manner 
than  that  of  drying.  The  preparation  is  allowed  to  freeze  at  a 
temperature  of  6,  8, 10,  or  15°  C.,  according  to  necessity,  until 
it  assumes  a  consistency  which  will  permit  fine  sections  to  be 
made  with  a  cooled  razor.  The  object  is  more  convenient  to 
handle  if  it  is  allowed  to  freeze  on  a  strip  of  cork ;  it  is  also 
judicious  to  make  use  of  an  artificial  freezing  mixture.  Nerves 
and  muscles  have  been  treated  in  this  manner  with  good  results 
(Chrzonszczewsky,  Cohnheim).  Glands,  such  as  salivary  glands, 
livers,  kidneys,  spleens,  the  lungs,  the  skin,  and  the  bodies  of 
embryos  also  afford  excellent  appearances  (Kolliker)  ;  likewise 
ganglia  (Arnold).  Indifferent  media,  such  as  iodine  serum,  are 
to  be  used  in  examining  the  sections. 


Section 


METHOD  OF  INJECTING. 

OF  the  greatest  value  for  histological  studies  is  the  artificial 
filling  of  the  vascular  systems  of  the  part  to  be  examined  with 
colored  masses  ;  a  procedure  which,  unfortunately,  is  still  too 
much  neglected  by  many,  inasmuch  as  without  having  obtained 
the  necessary  practice,  ;t  may  here  and  there  appear  as  though 
such  a  procedure  were  somewhat  superfluous  —  a  luxurious  ad- 
junct. And  yet  this  important  accessory  should  never  be  neg- 
lected in  any  investigation  which  is  at  all  accurate  of  normal  or 
pathological  textural  relations  ;  for  much  in  the  construction  of 
an  organ  at  once  assumes  the  greatest  clearness  and  intelligibili- 
ty after  its  capillary  system  has  been  filled,  and  the  desired  dis- 
closures with  regard  to  the  vascular  abundance  or  poverty  of  a 
part  are  at  once  obtained.  The  art  of  injecting  can  only  be 
learned,  and  its  execution  is  by  no  means  easy.  Much,  indeed 
the  greater  part,  depends  on  apparently  unimportant  expedients, 
on  little  artifices,  as  well  as  on  a  skill  only  to  be  obtained  by 
practice.  Nevertheless,  with  the  necessary  perseverance,  and 
by  not  being  discouraged  by  the  almost  unexceptionably  unsuc- 
cessful first  attempts,  one  soon  attains  the  desired  skill,  espe- 
cially if  one  renounces  the  idea  of  obtaining  perfectly  beautiful 
injections  at  the  beginning.  Success  is  gradually  more  and 
more  readily  obtained,  and  the  satisfaction  derived  from  the 
little  work  of  art  which  is  finally  produced,  has  already  been  for 
many  the  incentive  to  further  investigations. 

In  the  following  pages  we  shall  attempt  to  bring  before  the 
reader  the  most  important  of  the  technicalities  of  injecting,  and 
to  render  especially  prominent  that  which  we  have  learned  from 
our  own  experience  in  regard  to  this  subject.  At  the  same 
time  we  are  quite  willing  to  admit  that  others  might  have  re- 
placed many  things  that  are  here  noticed  with  much  that  would 


170  SECTION    NINTH. 

perhaps  have  been  better.  Although  all  such  directions  arc  not 
capable  of  thoroughly  supplying  that  which  may  be  obtained 
much  more  rapidly  from  the  practical  instruction  of  an  expe- 
rienced teacher,  they  will,  nevertheless,  present  serviceable 
hints  to  many  autodidacts. 

It  will  not  be  without  interest,  however,  to  previously  give  a 
cursory  glance  at  the  history  of  the  origin  of  this  art. 

The  art  of  injecting,  filling  the  canal  systems  of  the  body 
with  colored  or  other  readily  recognizable  masses,  is,  in  its  first 
crude  commencement,  relatively  an  old  one.  Ilyrtl,  in  his  im- 
portant "Ilandbuch  der  praktischen  Zergliederungskunst," 
Wien,  1860,  has  given  us  an  accurate  and  interesting  his- 
tory of  this  process.  As  early  as  the  seventeenth  century,  wax 
and  also  mercury  were  used  for  this  purpose.  Gelatine  was 
first  employed  for  injections  in  the  beginning  of  the  eighteenth 
century. 

Among  the  older  anatomists,  the  Hollander,  Kuysch  (1638- 
1731),  through  his  methods  of  injecting,  obtained  great  renown 
— undeservedly,  as  we  are  at  present,  after  accurate  historical 
investigation,  obliged  to  say,  like  so  many  of  the  celebrities  of 
older  and  newer  times.  Tallow  (tempered,  in  part,  with  wax) 
colored  with  cinnabar  formed  the  mass  used  by  him.  IS". 
Lieberkiihn  (1711-1746),  on  the  contrary,  accomplished  con- 
siderable for  his  time,  as  early  as  the  first  half  of  the  eighteenth 
century.  Even  at  the  present  time  his  preparations  deserve  to 
be  called  excellent,  as  we  are  assured  by  Hyrtl,  the  most  com- 
petent investigator  in  this  department.  He  made  use  of  a  mix- 
ture of  wax,  colophony,  and  turpentine,  and,  as  a»  coloring 
medium,  cinnabar.  At  a  more  recent  period,  Sommering,  Dol- 
linger,  and  Berres  accomplished  considerable  in  this  department. 
Among  those  more  recently  engaged  in  this  direction,  the  name 
of  Ilyrtl  shines  above  all  others.  Others  may  be  honorably 
associated  with  him,  as,  for  example,  Quekett,  Gerlach,  Thiersch, 
Beale,  etc. 

Naturally,  the  method  of  injecting  interests  us  here  only  in 
so  far  as  it  is  adapted  for  microscopico-histological  studies,  so 
that  we  shall  pass  over  with  entire  silence  the  technicology  of 
coarser  injections. 


METHOD    OF    INJECTING.  171 

Among  the  numerous  methods,  two  kinds  may  be  distin- 
guished. 

1.  Mixtures  which  are  fluid  when  warmed,  and  again  become 
solid  when  cooled. 

2.  Mixtures  which  flow  when  cold. 

Among  the  materials  of  the  first  kind,  resinous  and  gelatinous 
substances  have,  as  was  above  remarked,  come  into  use.  Hyrtl, 
who,  among  the  living,  has  had  the  greatest  experience  in  this 
department,  informs  us  that  the  former  renders  excellent  service 
in  the  injection  of  glandular  organs  and  all  capillary  vessels  of 
larger  diameter ;  but,  on  the  contrary,  in  other  parts  of  the 
body — for  example,  in  filling  the  subserous  blood-vessels  or 
those  of  the  mucous  membranes  of  the  air-passages,  the  oeso- 
phagus, the  stomach,  the  perichondrium,  the  medulla  of  bones 
and  of  the  testicle — they  are  unserviceable.  It  is  altogether  an 
error  to  believe  that  a  certain  injection  mixture  is  equally  use- 
ful for  all  organs. 

The  Vienna  anatomist  prepares  a  resinous  mixture  in  the  fol- 
lowing manner : — He  evaporates  the  purest  copal  or  mastic 
varnish  to  the  consistence  of  syrup,  and  then  mixes  with  it 
about  one-eighth  as  much  cinnabar,  which  is  to  be  carefully 
rubbed  with 'the  varnish  on  a  grinding-slab.  A  very  slight  ad- 
dition of  virgin  wax  is  also  made,  to  give  the  mixture  more  con- 
sistence. 

Some  time  ago  I  made  use  of  such  a  mixture,  by  way  of 
experiment,  and  saw  how,  with  a  little  practice,  very  handsome 
objects  might  be  obtained,  if  the  preparations  were  not  required 
for  finer  histological  studies,  but  rather  for  use  with  weaker 
magnifying  powers. 

Those  who  desire  to  investigate  the  finer  structure  of  the 
organ  to  be  injected  should,  therefore,  have  recourse  to  gela- 
tine. The  low  degree  of  temperature  at  which  a  gelatine  in- 
jection is  possible,  although  not  sufficient  for  the  resinous  in- 
jection, is  an  advantage  which  cannot  be  too  highly  prized. 
Very  properly,  therefore,  histologists  have  preferred  the  use  of 
gelatinous  mixtures  for  their  injections,  Sommering  and  Dol- 
linger  having  even  in  olden  times  accomplished  excellent  re- 
sults with  the  same.  The  subsequent  drying  which  ensues 


172  SECTION   NINTH. 

with  the  ordinary  older  methods  of  preservation  is  accompa- 
nied by  a  certain  shrinking  of  the  tubes  which  have  been  filled, 
an  evil  which  is  induced  by  the  loss  of  water ;  so  that  such 
objects  frequently  do  not  exhibit  the  full,  firm  appearance  pre- 
sented by  the  resinous  preparations.  Nevertheless,  the  much 
greater  readiness  with  which  the  watery  solution  of  gelatine 
passes  through  the  vessels  whose  walls  are  moistened  with  water 
is  an  advantage  which  can  be  obtained  with  no  other  mixture 
which  solidifies,  especially  for  organs  with  narrow  capillaries. 
Moreover,  this  shrinking  may  be  considerably  limited  by  care- 
ful mounting. 

Disregarding  the  coloring  materials  at  present,  in  order  to 
prepare  such  a  solution  of  gelatine  and  afterwards  make  use 
of  it,  several  precautionary  measures  are  necessary. 

Isinglass,  as  a  relatively  pure  gelatine,  has  been  frequently 
used.  It  is  in  no  wise  necessary,  and  its  high  price  and  the 
slowness  with  which  it  hardens  in  cooling  are  to  be  designated 
as  disadvantages.  More  recently  I  have  frequently  used  the 
thin,  transparent  gelatine  tablets  which  are  met  with  in  com- 
merce as  "  Gelatine  de  Paris,"  and  which  constitute,  it  is  true,  a 
mixture  which  is  also  not  to  be  numbered  among  the  cheapest. 
The  latter  may  be  formed,  however,  from  the  better  sorts  of 
ordinary  Cologne  gelatine. 

For  dissolving  gelatine  the  process  most  to  be  recommended 
is  the  following  : — 

The  gelatine  is  to  be  broken  to  pieces  and  then  soaked  in  dis- 
tilled or  rain  water  for  several  hours.  The  water  is  to  be  poured 
off  and  renewed,  the  gelatine  is  then  to  be  dissolved  in  a  water 
bath,  never  immediately  over  the  fire,  and  the  solution  filtered 
through  flannel  into  a  porcelain  dish.  The  coloring  material, 
the  necessary  directions  for  which  follow  further  below,  is  to  be 
added  to  the  solution  while  it  is  still  warm.  The  consistence 
which  is  to  be  given  to  the  gelatine  mixture  should  be  dependent 
on  the  individual  circumstances.  A  thin  gelatine  fluid  is  suffi- 
cient, if  a  pulverized  granular  coloring  matter  is  added  in  the 
form  of  a  thick  pulp.  If  the  coloring  material  is  directly  preci- 
pitated in  the  injection  fluid  by  pouring  together  solutions  of 
two  kinds  of  substances,  a  saturated  gelatine  fluid  should  be 


METHOD    OF    INJECTING.  173 

employed  With  a  little  practice  one  soon  learns  to  hit  upon 
the  proper  proportions. 

In  using  such  an  injection  fluid  it  is  to  be  warmed  in  the  same 
manner,  for  which  purpose  the  same  dish  may  be  used  several 
times  in  rapid  succession.  Such  a  fluid  cannot  be  kept  for  a 
long  time,  however  (even  in  a  camphorated  atmosphere),  without 
moulding,  or  even  without  losing  its  former  homogeneous  con- 
stitution, which  is  so  important ;  so  that  one  is  often  put  to  the 
unpleasant,  time-consuming  necessity  of  preparing  the  gelatine 
fluid  anew.* 

For  the  further  treatment  of  specimens  injected  with  gelatine, 
see  the  end  of  this  section. 

Quite  a  variety  of  coloring  materials  may  be  advantageously 
added  to  the  gelatine  fluid ;  they  will  be  mentioned  further 
below. 

The  use  of  injection  mixtures  which  solidify  on  cooling  always 
consumes  time,  as  was  remarked,  and  requires  a  variety  of 
arrangements.  The  discovery  of  a  material  which  is  fluid  when 
cold,  and  which  may  be  used  at  any  time,  must  therefore  appear 
to  be  of  great  value.  A  number  of  such  mixtures  have  been 
invented  and  recommended  in  the  course  of  time. 

"We  will  first  mention  a  process  practised  by  Bowman,  the 
English  histologist,  which,  although  it  may  be  momentarily  em- 
ployed, is  less  serviceable  for  producing  a  good  injection  than 
for  coloring  the  blood-vessels  of  an  organ  and  rendering  them 
visible  for  microscopic  examination.  This  method  consists  in 
forcing  two  solutions  of  salts  after  each  other  through  the  same 
vascular  system,  in  which  a  lively  colored  precipitate  is  thus 
produced.  Bowman  used  for  this  purpose  the  acetate  of  lead 
and  the  chromate  of  potash.  A  few  experiments  which  I  once 
made  with  this  method  gave  a  satisfactory  view  of  the  course  of 
the  vessels.  But  such  a  preparation  is  by  no  means  beautiful. 

For  his  cold  injections,  as  he  informs  us  in  his  "  Zergliede- 
rungskunst,"  Hyrtl  also  employs  the  previously  mentioned  re- 
sinous mixture,  to  which  he  gives  the  consistence  of  an  ordinary- 
coarse  injection  fluid  by  the  addition  of  a  litte  wax  and  red  lead. 
He  rubs  a  portion  of  the  same  in  a  dish,  with  the  addition  of 

*  One  of  Thiersch's  most  recent  recipes  follows  further  below  (p.  182). 


174  SECTION   NINTH. 

ether,  to  the  consistence  of  syrup.  He  then  adds  the  coloring 
material,  in  about  the  proportion  of  1:8,  and  again  rubs  the 
whole  with  ether  until  the  mixture  becomes  completely  fluid. 
Hyrtl  commends  the  facility  and  convenience  of  manipulation  of 
this  method.  In  consequence  of  the  evaporation  of  the  ether,  the 
injected  organ  is  ready  for  examination  in  a  quarter  of  an  hour. 

I  have  of  late  made  the  most  extended  use  of  a  mixture  re- 
commended by  Beale  ("  The  Microscope  in  its  Application  to 
Practical  Medicine."  London,  1858,  p.  67),  which  is  composed 
of  glycerine,  water,  and  alcohol,  for  filling  the  smaller  vascular 
systems.  This  mixture  excels  all  others  with  which  I  am  ac- 
quainted for  its  facility  of  penetration,  besides  which  it  affects 
the  tissues  less  than  any  of  the  mixtures  in  use.  As  the  mixture 
does  not  become  decomposed  or  altered  in  any  way,  it  may  be 
preserved  for  any  desirable  length  of  time.  It  is  par  excellence 
the  histologist's  injecting  fluid,  and  when  the  preparations  are 
mounted  moist  they  present  a  most  exquisite  appearance.  It 
has  also  afforded  me  very  passable  results  when  mounted  dry  by 
means  of  Canada  balsam  prepared  in  a  special  manner.  Still 
the  gelatine  fluids  are  preferable  for  the  latter  preparations, 
and,  in  consequence  of  their  consistence,  they  are  indispensable 
for  injecting  the  larger  organs. 

Having  discussed  the  injecting  fluids  which  arc  at  present 
generally  made  use  of,  let  us  now  pass  to  the  consideration  of 
the  coloring  materials  which  may  be  employed  with  the  same. 
These  coloring  substances  may  be  divided  into  granular,  per- 
mitting of  examination  only  with  incident  light,  and  transparent, 
suitable  for  ordinary  histological  investigations.  Those  of  the 
first  series  are  very  numerous  and  were  alone  employed  for  the 
older  injections.  The  number  of  the  latter  is,  on  the  contrary, 
much  smaller,  consisting  at  the  present  time  of  only  a  few 
coloring  materials. 

If  resinous  mixtures  are  used,  it  is  most  convenient  to  employ 
the  finest  oil  colors  for  artists,  which  are  to  be  purchased  in 
thin  leaden  tubes — a  procedure  made  use  of  by  Hyrtl.  Among 
these  "  colors  in  tubes,"  the  Vienna  naturalist  recommends  for 
red,  Chinese  vermilion ;  for  yellow,  orange  chrome  yellow  ;  for 
green,  emerald  green  and  verdigris ;  for  white,  Nottingham 


METHOD    OF   INJECTING.  175 

white  and  Cremnitz  white  ;  for  blue,  a  mixture  which  he  pre- 
pares from  the  last  white  color  and  Prussian  blue. 

These  colors  are  expensive,  it  is  true,  but  are  of  a  fineness 
such  as  no  one  can  prepare  for  one's  self.  They  are  therefore 
to  be  designated  as  of  the  first  rank  for  opaque  injections. 

If  gelatine  is  used  as  the  solidifying  substance,  it  is  customary 
to  employ  red,  yellow,  or  white  fluids. 

a.  Red  Mixture  (Cinnabar). 

Cinnabar  is  most  commonly  employed  for  this  purpose. 
Commencing  with  a  small  quantity  of  a  fine  quality,  it  is  to  be 
rubbed  up  as  carefully  as  possible  in  a  mortar,  with  the  gradual 
addition  of  water,  and  the  process  continued  in  this  manner. 
A  little  carmine  may  be  rubbed  up  with  it,  to  heighten  the 
color.  The  coloring  matter  is  then  to  be  gradually  added  to 
the  warm  gelatine  solution,  which  is,  at  the  same  time,  to  be 
carefully  stirred.  It  is  a  common  fault  of  beginners  that  they 
use  too  little  cinnabar,  and  hence  they  obtain  an  injection  fluid 
with  which  separated  scattered  granules  of  coloring  matter 
afterwards  appear  in  the  vessels.  A  good  cinnabar  injection 
should,  on  the  contrary,  yield  a  coherent  coralline  red  color. 
In  consequence  of  its  considerable  weight,  cinnabar  has  the  un- 
pleasant peculiarity  of  collecting  at  the  bottom  of  the  gelatine 
solution,  so  that  it  is  necessary  to  stir  the  mass  before  its  use. 

None  of  the  other  opaque  coloring  materials  should  be  used 
in  the  form  of  the  commercial  preparations,  unless  they  can  be 
given  to  a  professional  color-rubber  for  pulverization,  as  it  is 
otherwise  impossible  to  reduce  the  granules  to  the  necessary 
fineness.  It  is  much  preferable  to  procure  them  by  careful 
precipitation  from  diluted  solutions. 

5.  Yellow  Color  (Chrome  yellow). 

I  regard  this  as  the  best  and  most  readily  manageable  of  all 
the  opaque  coloring  materials.  In  order  to  obtain  a  good 
chrome  yellow,  36  parts  by  weight  of  sugar  of  lead  may  be 
dissolved  in  2  ounces  of  water,  and  likewise,  in  the  same  quan- 
tity of  water,  15  parts  of  red  chromate  of  potash.  By  carefully 
mixing  these  fluids,  preferably  in  a  high  glass  cylinder,  a  very 


176  SECTION    NINTH. 

finely  granulated  chromate  of  lead  is  produced,  which  is  gradu- 
ally deposited  at  the  bottom  of  the  vessel.  This  is  to  be  washed 
with  distilled  water  and  then  added,  in  the  form  of  a  thick 
slime,  to  the  gelatine  solution. 

Harting  (in  his  work  on  the  Microscope,  Yol.  II.,  p.  123)  gives 
the  following  recipe  (which  I  have  also  found  to  be  service- 
able):— 

4  ounces  1-J-  drachm  of  acetate  of  lead,  or  sugar  of  lead,  is  to 
be  dissolved  in  a  quantity  of  water  sufficient  to  make  the  whole 
volume  16  ounces. 

2  ounces  1  drachm  28  grains  of  bichromate  of  potash  are  to 
be  dissolved  in  a  quantity  of  water  sufficient  to  make  the  whole 
volume  32  ounces.     In  preparing  the  injecting  fluid,  take  one 
part  by  measure  of  the  solution  of  sugar  of  lead,  2  parts  by 
measure  of  the  solution  of  chromate  of  potash,  and  likewise  2 
parts  by  volume   of  a  saturated  solution  of  gelatine.      The 
chrome-yellow  is  to  be  first  precipitated  in  a  special  vessel,  and 
afterwards  added  to  the  gelatine.      The  precipitated  chrome- 
yellow  should  not  be  allowed  to  stand  too  long,  as  it  assumes  a 
coarse  granular  form,  in  consequence  of  the  conglomeration  of 
the  colored  molecules. 

c.   While  Color.     Carbonate  of  Lead.    Zinc  White.    Sulphate 

of  Baryta. 

A  serviceable  white  fluid  can  only  be  obtained  with  difficulty, 
as  in  most  of  them  the  granules  are  usually  too  coarse.  liar- 
ting,  who  instituted  a  series  of  experiments  on  this  subject,  gives 
the  following  recipe  for  producing  a  useful  carbonate  of  lead : — 

4  ounces  1£  drachm  of  the  acetate  of  lead  are  to  be  dissolved 
in  water,  so  that  the  whole  corresponds  to  a  volume  of  16  ounces. 

3  ounces  1|  drachm  of  carbonate  of  soda  are  to  be  dissolved 
in  water,  and  the  whole  likewise  made  up  to  16  ounces. 

For  the  injection  fluid,  take  one  part  by  measure  of  the  first 
solution,  the  same  quantity  of  the  second,  and  combine  them 
with  two  parts  of  gelatine  solution.  Harting  remarks  concerning 
this  fluid,  that  it  passes  through  the  vessels  better  than  white 
lead  combined  with  gelatine. 

I  formerly  obtained  tolerable  injections  with  finely-pulverized 


METHOD    OF   INJECTING.  177 

zinc  white.  I  have  not  used  this  coloring  material,  however, 
for  years. 

As  a  very  fine  white,  although  the  color  does  not  assume 
such  complete  uniformity,  I  recommend  the  sulphate  of  baryta. 
I  made  the  most  extended  use  of  this  material  years  ago,  and  am 
inclined  to  prefer  it  to  the  chrome-yellow,  when  it  is  necessary  to 
have  a  finely -granulated  and  therefore  readily  penetrating  fluid. 

I  employ  the  following  process : — The  salt  in  question  is  to 
be  precipitated  from  about  4  to  6  ounces  of  a  cold  saturated 
solution  of  chloride  of  barium,  in  a  glass  cylinder,  by  the  care- 
ful addition  of  sulphuric  acid.  After  standing  for  some  time, 
nearly  the  whole  of  the  fluid,  which  has  again  become  clear,  is 
to  be  poured  off,  and  the  remainder,  with  the  sulphate  of  ba- 
ryta, which  is  deposited  at  the  bottom  of  the  vessel,  is  to  be 
added,  in  the  form  of  a  thick  slime,  to  about  an  equal  volume, 
of  a  concentrated  solution  of  gelatine. 

d.    Chloride  of  Silver. 

Teichmann,  in  his  excellent  work,  mentions  a  new,  very  effi- 
cient, although  expensive  injecting  mixture  of  chloride  of  silver. 
He  commends  the  same  as  rendering  excellent  service  in  certain 
cases,  and  says  that  its  molecules  possess  a  very  considerable 
fineness,  occasionally  similar  to  those  of  chyle.  It  is  an  unplea- 
sant circumstance  that  the  mixture  becomes  black  from  the 
action  of  the  light  and  sulphuretted  hydrogen.  But,  like  sul- 
phate of  baryta,  the  combination  is  so  fixed  that  decomposition 
does  not  take  place  with  the  employment  of  reagents,  and  the 
specimens  may  be  preserved  in  chromic  acid,  etc. 

Three  parts  of  nitrate  of  silver  in  solution  are  to  be  combined 
with  the  solution  of  gelatine,  and  then  one  part  of  common  salt 
is  to  be  added. 

Considerably  superior  to  these  granular  substances  are  the 
transparent  coloring  materials,  that  is,  those  whose  particles  are 
so  fine  that  even  with  high  magnifying  powers  the  injected 
vessels  still  show  a  homogeneous  color.  Such  injections  are 
particularly  to  be  recommended  for  histological  investigations, 
as  it  is  by  their  use  only  that  it  is  possible  to  recognize  the 

remaining  structural  conditions,  while  a  complete  injection  with 
12 


178  SECTION    NINTH. 

opaque  mixtures  conceals,  more  or  less,  the  finer  structure  of  the 
organ.  They  will  be  substituted  for  the  granular  coloring 
materials  by  any  one  who  has  used  them  a  few  times  when  well 
prepared.  The  reproach  which  has  here  and  there  been  made 
concerning  these  colors  that  they  transude,  refers  only  to  those 
which  are  badly  made,  but  is  not  applicable  to  good  transparent 
materials.  Unfortunately,  the  number  of  these  is,  as  yet,  but 
very  small.  Until  recently,  besides  the  soluble  Prussian  blue, 
there  was  only  a  red  coloring  material,  carmine,  known.  Pro- 
fessor Thiersch,  who  has  earned  so  much  credit  by  his  methods 
of  injecting,  has  recently  enriched  us  with  a  soluble  yellow  and 
green,  and  was  so  friendly  as  to  communicate  to  me  their  com- 
position. 

"We  shall  first  speak  of  such  of  these  coloring  materials  as  are 
adapted  for  gelatine  injections. 

A  number  of  different  mixtures  are  at  present  known  under 
the  name  of  transparent  Prussian  blue.  Of  these,  the  second 
receipt  deserves  but  little  recommendation,  as  the  blue  color 
gradually  fades,  especially  when  the  preparation  is  preserved  in 
glycerine.  The  first  coloring  material  is,  on  the  contrary,  excel- 
lent, and  the  last  is  also  very  much  extolled. 

1.  TkierscKs  Prussian  JSlue  with  Oxalic  Acid. 

The  best  receipt  with  which  I  have  become  acquainted  runs 
as  follows : — 

Prepare  a  cold  saturated  solution  of  the  sulphate  of  the  pro- 
toxide of  iron  (A),  a  similar  one  of  ferrocyanide  of  potassium, 
that  is,  prussiate  of  potash  (B),  and  thirdly,  a  saturated  solution 
of  oxalic  acid  (C).  Finally,  a  warm  concentrated  solution 
(2  :  1)  of  fine  gelatine  is  necessary.  About  half  an  ounce  of 
the  gelatine  solution  is  to  be  mixed  in  a  porcelain  dish  with  6 
ccm.  of  the  solution  A.  In  a  second  larger  dish,  one  ounce  of 
the  gelatine  solution  is  to  be  combined  with  12  ccm.  of  the  so- 
lution B,  to  which  12  ccm.  of  the  oxalic  acid  solution  C  is  after- 
wards added. 

When  the  mixtures  in  both  dishes  have  cooled  to  about  25  or 
32°  C.,  the  contents  of  the  first  dish  are  to  be  added  dropwise, 
and  with  constant  stirrirg,  to  the  mixture  in  the  latter.  After 


METHOD    OF   INJECTING.  179 

complete  precipitation,  the  deep  blue  mixture  which  is  formed 
is  to  be  heated  to  70  or  100°  C.  for  a  time  and  constantly 
stirred  ;  finally,  it  is  to  be  filtered  through  flannel. 

The  injecting  fluid  thus  obtained  keeps  excellently  in  Canada 
balsam.  The  depth  of  its  color  may  be  readily  modified  to  any 
desired  degree  by  adding  a  larger  quantity  of  the  gelatine  so- 
lution, 

2.  Prussian  Blue  dissolved  in  Oxalic  Acid. 

A  pure  Prussian  blue,  preferably  one  that  has  been  obtained 
by  precipitation,  is  to  be  dissolved  with  the  necessary  quantity 
of  oxalic  acid.  The  color  is  certainly  very  intense,  so  that  a 
moderate  quantity  is  sufficient  to  give  a  lively  blue  color  to  a 
dish  of  gelatine  solution.  This  mixture,  like  all  transparent 
coloring  matters,  in  consequence  of  the  infinite  fineness  of  its 
granules,  readily  passes  through  the  fine  capillaries. 

Harting  recommends  the  following  method  (in  which  the 
quantity  of  oxalic  acid  appears  too  great) : — 

Take  1  part  of  Prussian  blue,  1  part  oxalic  acid,  12  parts 
water,  and  12  parts  concentrated  solution  of  gelatine.  First, 
rub  the  oxalic  acid  in  a  mortar,  and  then  add  the  Prussian  blue. 
Thereupon  the  water  is  to  be  gradually  added  while  constantly 
rubbing,  and  finally  this  blue  fluid  is  to  be  added  to  the  gelatine. 

3.  Prussian  Blue  from  Sulphate  of  Peroxide  of  Iron  and 
Ferrocyanide  of  Iron. 

This  color,  which  was  first  employed  by  Schroder  van  der 
Kolk  and  afterwards  recommended  by  Harting,  is  a  good  one, 
although  it  requires  somewhat  more  time  for  its  preparation. 
Its  granules  are  extremely  fine,  and  hence  it  flows  very  readily. 
Nevertheless,  the  older  preparations  of  my  collection  have 
lately  become  considerably  faded,  so  that  I  rather  prefer 
Thiersch's  blue. 

I  have  used  the  blue  made  exactly  according  to  Harting's 
receipt,  so  that  I  can  only  recommend  that. 

3-jjr  ounces  of  sulphate  of  iron  is  to  be  dissolved  in  from  20  to 
25  ounces  of  water  and  slightly  warmed.  Then,  by  the  addition 
of  4f  drachms  of  sulphuric  acid  of  1.85  sp.  wt.,  and  the  neces- 


180  SECTION   NINTH. 

sary  quantity  of  nitric  acid,  the  iron  is  changed  to  an  oxy-salt. 
A  sufficient  quantity  of  water  is  then  added  to  make  the  whole 
volume  of  fluid  40  ounces. 

3  ounces  6J  drachms  of  ferrocyanide  of  potassium  (yellow 
prussiate  of  potash)  is  to  be  dissolved  in  water,  and  the  whole 
volume  of  fluid  increased  to  80  ounces. 

1  part  by  measure  of  the  solution  of  oxide  of  iron,  2  parts 
by  measure  of  the  solution  of  yellow  prussiate  of  potash,  and 
likewise  2  parts  of  the  gelatine  solution  are  to  be  employed. 

In  order  to  prevent  the  gelatine  from  collecting  in  lumps 
and  becoming  ropy,  I  recommend  the  following  method.  The 
solution  of  ferrocyanide  of  potassium  should  be  warmed  and 
combined  with  the  heated  solution  of  gelatine.  The  solution 
of  sulphate  of  protoxide  of  iron  is  then  to  be  added  by  drops, 
and  while  constantly  stirring  the  mixture,  which  is  finally  to 
be  filtered  through  flannel. 

4.  Soluble  Prussian  Blue. 

This  is  obtained  by  adding  to  a  solution  of  ferro-cyanide  of 
potassium  in  excess,  a  solution  of  perchloride  of  iron,  or  of 
another  oxy-salt.  The  precipitate  is  to  be  collected  on  a  filter, 
and  after  the  fluid  has  filtered  away,  again  washed  with  dis- 
tilled water  till  (after  the  removal  of  the  salts  which  were 
in  the  solution)  a  blue  color  begins  to  appear  in  the  filtrate. 
The  blue  mass  which  is  thus  obtained  becomes  so  finely  divided 
in  water  that  the  impression  of  a  solution  arises. 

Several  years  ago,  Briicke  recommended  the  following 
receipt  for  preparing  such  a  soluble  Prussian  blue : — 

Ferrocyanide  of  potassium  217  grammes,  dissolved  in  1 
litre  of  distilled  water. 

Perchloride  of  iron  10  grammes,  in  1  litre  of  distilled  water. 

Sulphate  of  soda,  a  cold  saturated  solution. 

One  volume  of  each  of  the  two  first  solutions  is  to  be  mixed 
with  one  volume  of  the  soda  solution.  The  iron  and  soda 
solution  is  then  to  be  gradually  mixed  with  the  ferro-cyanide 
and  soda  solution,  with  constant  stirring. 

An  extremely  fine  blue  is  obtained,  but  I  am  inclined  to  place 
it  after  that  of  Thiersch,  so  far  as  its  durability  is  concerned. 


METHOD    OF    INJECTING.  181 

Sections  of  organs  injected  in  tins  manner  often  appear 
colorless,  but  subsequently  assume  the  blue  color  in  oil  of  tur- 
pentine. 

A  good  carmine  mixture  remains  unexcelled  as  a  transparent 
red.  This  substance  requires  careful  preparation,  it  is  true, 
and  when  not  properly  prepared  it  is  completely  useless,  as  it 
transudes  in  all  directions. 

5.  GerlacJJs  Carmine  Fluid. 

Professor  Gerlach,  the  inventor  of  the  method  of  injecting 
with  carmine,  has  had  the  kindness  to  communicate  to  me  the 
composition  of  the  fluids  used  by  him,  and  to  permit  me  to 
make  them  public. 

Dissolve  5  grammes  of  the  finest  possible  carmine  in  4  gram- 
mes of  water  and  -J  grm.  of  liquor  ammonia.  The  mixture 
should  be  allowed  to  stand  for  several  days  in  a  vessel  not  closed 
air-tight,  and  then  mixed  with  a  solution  containing  6  grammes 
of  fine  white  French  gelatine  to  8  grm.  of  water.  A  few  drops 
of  acetic  acid  are  then  to  be  added,  and  the  mixture  injected  at 
a  temperature  of  40-45°  C. 

I  have  made  the  most  extended  use  of  carmine  fluids  for  a 
long  time,  and  recommend,  after  many  trials,  the  following 
method : — 

Have  ready  a  solution  of  ammonia  and  one  of  acetic  acid,  of 
which  the  number  of  drops  necessary  to  neutralize  each  other 
has  been  previously  determined. 

Take  30-40  grains  of  the  finest  carmine,  a  determined  num- 
ber of  drops  of  the  solution  of  ammonia  (the  quantity  may  be 
greater  or  smaller  as  may  be  desired),  and  about  half  an  ounce 
of  distilled  water ;  all  of  these  are  to  be  put  in  a  mortar,  and 
the  carmine  dissolved  by  rubbing.  The  solution  is  then  to  be 
filtered,  which  requires  several  hours,  and  a  considerable  loss  of 
ammonia  ensues  in  consequence  of  evaporation. 

The  ammoniacal  solution  of  carmine  is  to  be  mixed  with  a 
filtered,  moderately-heat  d  concentrated  solution  of  fine  gela- 
tine while  stirring.  The  whole  is  then  to  be  slightly  heated  on 
the  water-bath,  and  the  number  of  drops  of  the  acetic  acid  so- 
lution necessary  to  neutralize  the  original  solution  of  ammonia 


182  SECTION   TOOTH. 

is  to  be  slowly  added,  still  constantly  stirring  the  mixture.  By 
this  procedure  a  precipitation  of  the  carmine  in  an  acid  solu- 
tion of  gelatine  is  obtained.  If  it  be  intended  to  inject  organs 
of  strongly  alkaline  reaction  (for  instance,  those  of  human 
bodies  which  have  been  dead  for  some  time),  the  acidity  of  the 
fluid  may  be  increased  by  the  further  addition  of  several  drops 
of  acetic  acid.  The  proportion  of  gelatine  is  to  be  increased  or 
diminished  according  as  a  deeper  or  brighter  red  is  desired. 

This  simple  procedure  never  fails,  if  the  carmine  used  be  of 
a  good  sort  (which  is  of  great  importance),  and  an  increase  of 
temperature  beyond  about  45°  C.  be  avoided  during  the  in- 
jection. 

For  the  preservation  of  such  a  fluid — and,  we  might  add,  of 
other  injection  fluids  containing  gelatine — Thiersch  recommends 
the  following  precautionary  measures  : — 

Sulphate  of  quinine  is  to  be  added  to  the  water  used  for  dis- 
solving the  gelatine,  in  the  proportion  of  two  grains  to  the 
ounce  of  dry  gelatine  ;  pieces  of  camphor  are  also  to  be  boiled 
in  it ;  when  the  preparation  of  the  injection  fluid  is  completed, 
more  camphor  is  to  be  added,  and,  finally,  several  pieces  of 
camphor  are  to  be  placed  on  the  mixture  when  solidified. 
Thus,  even  in  the  heat  of  summer,  decomposition  and  the  for- 
mation of  mould  may  be  prevented.  I  have  made  use  of  a 
camphorated  atmosphere  for  a  number  of  years,  and  can  only 
recommend  the  recipe  of  this  distinguished  technist. 

6.  ThierscJi }s  Transparent  Yellow. 

This  beautiful  yellow,  which  requires  some  care,  however,  to 
prepare  it  well,  is  to  be  obtained  in  the  following  manner : — 

Prepare  a  watery  solution  of  eliminate  of  potash,  in  the  pro- 
portion of  1 : 11  (A),  and  a  second  solution,  equally  strong,  of 
the  nitrate  of  lead  (B). 

Combine  one  part  of  the  solution  A  with  four  parts  of  a  con- 
centrated solution  of  gelatine  (about  20  ccm.  to  80)  in  a  dish. 
In  a  second  dish,  two  parts  of  the  solution  of  lead  (B)  is  to  be 
mixed  with  four  parts  of  gelatine  (about  40  ccm.  to  80). 

The  contents  of  both  dishes  are  then  to  be  .slowly  and  care- 
fully mixed  with  each  other  at  a  temperature  of  about  25-32° 


METHOD    OF    INJECTING.  183 

C.,  and  with  constant  stirring.  This  mixture  is  to  be  heated  to 
about  70  or  100°  C.,  on  the  water-bath,  for  a  considerable  time 
(half  an  hour  or  more),  and  finally  filtered  through  flannel. 

When  a  dish  of  this  yellow  mixture  has  stood  for  some  time, 
it  is  generally  necessary  to  heat  it  for  a  considerable  time  and 
filter  it  again,  in  order  to  render  it  serviceable.  I  have  used  a 
double  quantity  of  the  solutions  A  and  B  for  many  purposes 
with  advantage. 

7.  Hoyer's  Transparent  Yellow. 

Hoyer  recommends  the  following  mixture  as  a  yellow  of  the 
finest  division,  which  also  appears  transparent  in  the  smaller 
vessels  and  has  a  lively  color  : — 

Equal  parts  of  a  solution  of  gelatine,  a  concentrated  solution 
of  bichromate  of  potash,  and  the  same  of  sugar  of  lead  (the  neu- 
tral acetate  of  lead),  are  to  be  combined  with  each  other  in  such 
a  manner  that  the  solution  of  gelatine  and  that  of  the  bichro- 
mate of  potash  are  united,  and  then  heated  nearly  to  the  boiling 
point.  To  this  is  carefully  added  the  sugar  of  lead  solution, 
which  should  also  be  previously  warmed. 

8.  Thiersctts  Transparent  Green. 

Equal  parts  of  the  blue  gelatine  solution  as  used  by  Thiersch, 
and  the  yellow  one  mentioned  under  6,  when  carefully  mixed, 
heated  for  some  time,  and  then  filtered,  make  a  good  and  hand- 
some green. 

Many  transparent  coloring  materials  are  capable  of  a  more 
advantageous  application,  however,  than  being  combined  with 
gelatine.  They  are  combined  with  a  peculiar  mixture  which 
flows  when  cold,  and  in  this  manner  are  obtained  the  best  injec- 
tion fluids  yet  known  for  histological  investigations. 

As  we  have  made  frequent  use  of  them,  the  compositions  used 
follow. 

1.  Bealds  Ordinary  Blue. 

Dissolve  15  grains  of  ferrocyanide  of  potassium  with  1  ounce 
of  distilled  water  in  a  flask.  Dilute  from  J  a  drachm  to  2 
scruples  of  the  English  muriated  tincture  of  iron  with  another 


184  SECTION    NINTH. 

ounce  of  water.  It  is  well  to  have  this  tincture  of  sesquichloride 
of  iron  accurately  prepared  according  to  the  British  pharmaco- 
poeia, by  a  good  apothecary,  in  sufficient  quantity  to  last  for  some 
time.  The  latter  fluid  is  added  by  drops  to  the  former,  at  the 
same  time  shaking  it  smartly.  A  mixture  is  then  prepared  of 
water  2  ounces,  glycerine  1  ounce,  ordinary  (ethyl)  alcohol  1 
ounce,  and  methyl  alcohol  1|-  drachm.*  This  mixture  is  to  be 
carefully  added  to  the  blue  colored  fluid,  the  flask  being  smartly 
shaken  during  the  process,  and  the  charming  blue  injection 
fluid  is  ready  for  use. 

2.  Bealds  Finest  Blue. 

Beale  has  recently  ("  How  to  work  with  the  Microscope." 
Third  edition,  p.  200)  given  a  modified  formula  for  the  prepara- 
tion of  a  cold  flowing  blue  injection  fluid,  which,  when  well 
prepared,  surpasses  all  others  that  I  know  of  in  fineness,  so  that 
after  standing  quietly  for  weeks  the  appearance  of  a  solution 
remains  unchanged,  and  there  is  not  the  least  sediment  formed. 
I  prepare  it,  somewhat  modified,  in  the  following  manner  : — 

Combine  10  drops  of  the  muriated  tincture  of  iron  mentioned 
with  half  an  ounce  of  good  glycerine  in  a  flask ;  in  another 
flask  3  grains  of  ferrocyanide  of  potassium  dissolved  in  a  little 
water,  to  which  is  to  be  added  another  half  ounce  of  glycerine. 
Both  solutions  are  then  to  be  very  carefully  mixed  together,  shak- 
ing them  smartly,  and  finally  half  an  ounce  of  water  with  3 
drops  of  strong  muriatic  acid  is  to  be  added. 

3.  Richardson }s  Blue. 

B.  "Wills  Richardson  (Quart.  Journ.  of  Micr.  Science,  Vol.  8, 
p.  271)  recommends  another  composition. 

10  grains  of  pure  sulphate  of  iron  is  to  be  dissolved  in  1 
ounce  of  distilled  water,  and  32  grains  of  ferridcyanide  of  po- 
tassium in  another  ounce  of  water.  As  with  Beale's  blue,  these 
two  solutions  are  then  gradually  mixed  together  in  a  bottle,  the 
iron  solution  being  added  to  that  of  the  ferridcyanide,  and  mix- 
ture insured  by  frequent  agitation.  This  makes  a  beautiful 

*  The  methyl  alcohol  in  this  and  the  third  formula  is  a  superfluous  addition 
and  in  consequence  to  be  omitted. 


METHOD    OF    INJECTING.  185 

greenish  blue,  in  which  there  is  as  little  appearance  of  grannies 
to  be  recognized  with  the  naked  eye  as  in  Beale's  mixture. 
Then  the  mixture  mentioned  under  No.  1,  consisting  of  water, 
glycerine,  and  the  two  alcohols,  is  to  be  carefully  added  and 
considerably  shaken. 

4.  Mullens  Blue. 

"W.  Miiller  prepares  in  a  simple  way  a  cold  flowing  blue 
mixture  by  the  precipitation  of  soluble  Prussian  blue  from  a 
concentrated  solution  by  means  of  90  per  cent,  alcohol.  The 
coloring  matter  is  thus  precipitated  in  a  state  of  most  extreme 
fineness,  and  a  completely  neutral  fluid  is  obtained. 

5.  Bealds  Carmine. 

Mix  5  grains  of  carmine  with  a  few  drops  of  water,  and  when 
well  incorporated  add  from  five  to  six  drops  of  liquor  ammo- 
nia. To  this  solution  about  half  an  ounce  of  glycerine  is  to 
be  added,  and  the  whole  well  shaken.  Another  half-ounce  of 
glycerine,  containing  eight  or  ten  drops  of  concentrated  acetic 
or  hydrochloric  acid,  is  to  be  slowly  and  gradually  added  to  the 
carmine  solution,  frequently  shaking  during  the  mixture.  The 
carmine  thus  becomes  very  finely  granular,  and  the  whole 
assumes  a  bright  arterial  red  color.  For  its  dilution  a  mixture 
is  used  consisting  of  half  an  ounce  of  glycerine,  2  drachms  of 
ordinary  alcohol,  and  6  drachms  of  water. 

6.   White  Fluids. 

As  I  have  not,  as  yet,  been  able  to  find  a  third  transparent 
coloring  material  for  cold  flowing  injections,  I  have  used  an 
opaque  mass,  the  sulphate  of  baryta.  The  mass  is,  as  was  re- 
marked, very  finely  granular,  and  is  capable  of  being  combined 
with  a  blue,  if  it  be  desired  to  inject  the  arteries  and  veins 
separately.  I  employ  the  following  process : — 

The  salt  is  reprecipitated  from  a  cold  saturated  solution  of 
4  ounces  of  chloride  of  barium  by  adding,  drop-wise,  sulphuric 
acid.  After  standing  for  some  time  (12  to  24  hours)  in  a  tall 
cylindrical  glass  vessel,  it  is  deposited  at  the  bottom.  About 
half  the  fluid,  which  has  again  become  clear,  is  now  to  be  poured 


186  SECTION    NINTH. 

off,  and  the  remainder,  well  shaken  up,  is  to  "be  combined  with 
a  mixture  of  one  ounce  each  of  alcohol  and  glycerine. 

These  masses  * — we  repeat  it — are  distinguished  by  their 
great  permeability,  so  that  we  prefer  them  to  all  gelatinous  sub- 
stances for  the  injection  of  lymph  passages  and  glandular  canals. 
They  also  have  the  extraordinary  advantage  of  being  capable 
of  preservation  for  months  without  alteration,  so  that  they  are 
instantly  at  hand.  They  are  kept  in  small  bottles  with  well- 
fitted  glass  stoppers.  The  requisite  quantity  for  an  injection  is 
poured  into  a  porcelain  dish,  and  it  is  then  ready  for  use.f 

7.  Solution  of  Nitrate  of  Silver. 

Within  a  few  years  a  solution  of  nitrate  of  silver  has  been 
used  for  injections,  in  order  to  render  the  cells  of  vessels  visi- 
ble. The  animal  is  bled  to  death,  a  solution  of  nitrate  of  silver 
(0.25,  0.5-1  per  cent.)  is  then  injected,  which  is  to  be  followed 
after  a  few  minutes  by  a  stream  of  water ;  or,  a  mixture  of 
gelatine  and  a  solution  of  nitrate  of  silver  is  used,  in 

*  W.  Miiller,  in  his  excellent  monograph  on  the  spleen,  also  mentions  a  cold 
flowing,  brownish  red  mass,  which  is  obtained  by  precipitation  from  a  solu- 
tion of  the  chromate  of  copper  with  ferrocyanide  of  potassium.  Chromate  of 
copper  is  obtained  by  digesting  equivalent  portions  of  sulphate  of  copper  with 
chromate  of  potash,  and  washing  out  the  brown  precipitate.  The  latter 
readily  dissolves  in  chromic  acid  in  excess,  and  may  be  precipitated  from  the 
diluted  solution,  by  means  of  ferrocyanide  of  potassium,  in  the  form  of  an  ex- 
tremely fine  brownish-red  sediment  of  ferrocyanide  of  copper.  It  may  be  at 
once  injected,  without  further  addition  than  the  solution  of  bichromate  of 
potash  which  has  been  formed,  and  thus,  at  the  same  time,  serve  as  a  medium 
for  hardening  the  tissue. 

f  I  have  recently  employed  with  advantage  soluble  Prussian  blue  simply 
dissolved  in  water  for  the  injection  of  the  ducts  of  glands,  urinary  canals, 
and  biliary  plexuses,  also  for  lymphatic  canals.  10  grains  of  sulphate  of  iron 
dissolved  in  1  ounce  of  water,  32  grains  of  red  prussiate  of  potash  in  another 
ounce  of  water,  and  both  carefully  combined  (see  above),  make  a  good  fluid. 
If  the  canals  to  be  filled  are  very  fine,  double  the  quantity  of  each  salt  is  to  be 
added  to  each  ounce  of  water.  Glycerine  may  be  added  if  desirable.  The 
red  mixture  recommended  by  Kollmann  is  serviceable.  1  gramme  of  carmine 
is  to  be  dissolved  in  a  little  water  with  15-20  drops  of  concentrated  ammonia, 
and  diluted  with  20  com.  of  glycerine.  An  additional  20  com.  of  glycerine  is 
to  be  tempered  with  18-20  drops  of  strong  muriatic  acid  and  carefully  added 
to  the  carmine  solution,  at  the  same  time  shaking  the  latter  strongly.  It  may 
be  subsequently  diluted  by  the  addition  of  about  40  ccm.  of  water. 


METHOD    OF    INJECTING.  187 

order  to  gain  a  more  permanent  distention.  Sections  of  the 
organ  are  made  and  exposed  to  the  light,  and  then  hardened  in 
alcohol.  By  this  simple  method  the  entire  vascular  arrange- 
ment may  also  be  recognized  with  the  same  distinctness  as  by 
the  ordinary  injections  with  colored  masses. 

After  having  become  acquainted  with  the  fluids  used  for  in- 
jecting, and  the  manner  of  preparing  them,  we  now  pass  to  the 
consideration  of  the  apparatus  and  the  act  itself  of  injecting. 
All  who  have  frequently  practised  this  operation  will  agree 
with  us  that  a  very  simple  apparatus  is  all  that  is  required. 

Before  discussing  the  method  of  injecting  which  is  most  im- 
portant and  most  frequently  used,  namely,  that  by  means  of  the 
syringe,  it  is  necessary  to  mention  several  other  modern  pro- 
cesses which,  according  to  our  own  experience  and  that  of 
others,  may  be  practised  with  facility  and  success,  and  will, 
without  doubt,  lead  to  the  extension  of  our  knowledge  in  many 
directions — we  mean  the  self -injection  of  the  living  animal  and 
the  injection  by  means  of  constant  pressure. 

The  idea  was  sufficiently  obvious  of  permitting  the  escape  of 
a  definite  quantity  of  blood  from  the  body  of  the  living  animal 
by  opening  a  vein,  and  replacing  what  was  lost  by  an  innocuous 
colored  fluid,  so  that  the  contractions  of  the  heart  would  fill 
certain  vascular  districts  with  it  in  a  much  less  injurious  manner 
than  can  be  accomplished  by  the  human  hand. 

Chrzonszczewsky  made  us  acquainted  with  these  methods 
some  time  since.  They  consist  in  the  introduction  of  the  watery 
solution  of  the  carminate  of  ammonia. 

10  ccm.  of  blood  may  be  removed  from  the  jugular  of  a 
medium-sized  rabbit,  and  replaced  by  the  same  quantity  of  a 
solution  of  carmine,  by  means  of  the  syringe  to  be  mentioned 
below,  without  injury  to  the  blood  with  which  it  becomes 
mixed.  An  adult  animal  bears  15  ccm.,  a  dog  of  medium 
size,  25.  Even  during  the  injection,  the  reddening  may  be 
recognized  on  certain  portions  of  the  surface.  If  the  larger 
vessels  are  then  rapidly  ligated,  first  the  vein  and  then  the 
artery,  a  physiological  injection  of  the  blood  passages  is  ob- 
tained. The  kidneys,  spleen,  etc.,  may  be  advantageously 
treated  in  this  manner.  At  the  same  time,  this  carmine  injec- 


188  SECTION   NINTH. 

tion  may  be  accomplished  not  only  from  the  vascular  system, 
but  also  from  the  stomach,  rectum,  and  abdominal  cavity,  and 
in  amphibia  from  the  lymph  cavities. 

The  inventor  recommends  the  solution  of  2  drachms  of 
carmine  in  1  drachm  of  liquor  ammonia,  the  same  to  be 
diluted  with  one  ounce  of  water.  Naturally,  this  solution  is 
to  be  filtered  before  using.  The  organ  is  to  be  placed  in 
acidulated  alcohol  to  cause  the  granular  fixation  of  the  carmine. 

Such  injections  obtain  a  high  value  in  still  another  manner. 
N~ot  only  this  carmine  solution,  but  also  a  cold  concentrated 
solution  of  sulph-indilate  of  soda  is  rapidly  excreted  by  the 
kidneys,  and  the  latter  substance  also  into  the  biliary  passages, 
after  large  quantities  have  been  injected.  If  the  ureter  be 
ligated  immediately  after  injecting  the  rabbit,  and  the  animal 
killed  after  three-quarters  of  an  hour  to  one  hour,  the  entire 
system  of  urinary  canals  will  be  found  filled  with  carmine. 
In  injecting  the  biliary  passages  with  the  blue  fluid,  it  is 
unnecessary  to  apply  the  ligature.  In  both  cases,  however, 
it  is  necessary  to  wash  the  blood-vessels  subsequently,  and  to 
replace  the  original  coloring-matter  which  remains  in  them 
with  another.  The  organs  injected  with  blue  are  next  placed 
in  a  concentrated  solution  of  chloride  of  calcium,  and  then  in 
absolute  alcohol,  where  the  coloring  matter  becomes  fixed  in 

'  O 

fine  granules. 

Injecting  by  means  of  constant  pressure  also  has  great 
advantages  for  many  purposes.  First,  we  may  learn  by  this 
means  to  estimate  the  pressure  which  is  necessary  to  fill  certain 
portions  of  the  blood  and  lymph  passages,  or  of  the  glandular 
canals ;  then,  besides  a  very  high  pressure  we  can  also  use  a 
very  low  one,  and  finally  it  permits  of  making  the  injection 
with  extreme  slowness,  which  the  human  hand  refuses  to  do, 
in  consequence  of  fatigue. 

Beautiful  results  have  been  obtained  by  this  method  for  the 
lymphatic  passages  and  also  for  the  glandular  canals  (kidney 
and  liver). 

A  simple  way  of  making  such  injections  is  by  means  of  a 
graduated  glass  tube  (fig.  75  &),  which  should  not  be  too  small, 
held  by  a  support  (a).  To  the  lower  end  of  this  is  firmly 


METHOD    OF    INJECTING. 


189 


secured  an  india-rubber  tube  (c),  the  lower  extremity  of  which 
terminates  in  a  metallic  tube  which  can  be  closed  by  means  of 
a  cock  (fig.  75  d.  76)  ;  this  tube  should  fit  into  the  aperture  of 
the  canules  of  the  ordinary  injecting  apparatus.  The  caiiule 
should  be  tied  into  the  vessel  of  the  organ  to  be  injected,  in 
the  manner  hereafter  indicated,  and  placed  in  a  convenient 
position  near  the  glass  tube,  which  is  secured  in  a  perpen- 
dicular position,  having  been  previous- 
ly filled  to  a  certain  height  and  the 
stop-cock  turned  off.  The  end  of  the 
tube  is  to  be  cautiously  but  securely 
inserted  into  the  aperture  of  the  can- 
ule  and  the  cock  opened.  The  original 
pressure  may  be  maintained  or  increas- 
ed, as  necessity  may  require,  by  pour- 
ing in  more  fluid.  Such  an  arrange- 
ment may  be  left  to  itself  for  a  num- 
ber of  hours  or  even  days. 

If  it  be  desired  to  use  the  pressure 
of  a  column  of  mercury,  the  readily 
constructed  apparatus,  represented  in 
less  than  half  size  by  fig.  77,  is  to  be 
recommended.  A  glass  bottle  (a)  is 
to  be  closed  by  an  accurately  fitting 
cork  (preferably  of  gutta-percha)  per- 
forated by  two  holes.  Through  these 
holes  pass  two  glass  tubes  perpen- 
dicularly ;  one  of  them  (e),  which  is 
graduated,  and  slightly  funnel-shaped 
at  the  top,  extends  nearly  to  the  bottom 
of  the  bottle.  A  second  one  (f),  which 
is  bent  on  itself,  terminates  just  be- 
neath the  cork.  The  continuation  of 
the  external  portion  of  the  latter  tube 
is  formed  by  a  caoutchouc  tube  (g) 
firmly  secured  to  it,  at  the  termination 

of  which  the  above-mentioned  metallic  tube  with  a  stop-cock 
(h)  is  inserted  and  receives  the  canule  (a).    At  the  upper  f  un- 


Fig.  75.    Simple  injecting  appara- 
tus, with  a  glass  tube. 


190 


SECTION    NINTH. 


nel-shaped  opening  (e)  of  the  first  tube  is  placed  a  small  glasa 
funnel  (£),  supported  by  a  stand  (k] ;  the  funnel  is  prolonged 
by  means  of  a  caoutchouc  tube  (m),  into  the  lower  end  of  which 
is  secured  a  finely  pointed  glass  tube  (ri).  It  is  used  for  pour- 
ing in  the  mercury,  and  has  on  the  caoutchouc  tube  a  clamp 
(0),  or  preferably  a  screw-clamp. 

In  preparing  the  apparatus  for  use,  the  lower  part  of  the  glass 
vessel  is  filled  with  mercury  (d),  the  cock  of  the  delivery -tube 


Fig.  77.    Injecting  apparatus  with  a  column  of  mercury. 

is  then  opened  and  the  vessel  filled  to  the  upper  edge  with  the 
injecting  fluid.  The  cork  with  the  two  tubes  is  now  to  be  firmly 
pressed  into  position,  the  funnel-shaped  opening  of  the  perpen- 
dicular tube  being  at  the  same  time  securely  closed  by  the 
pressure  of  the  thumb,  care  being  also  taken  that  the  lower  end 


METHOD    OF   INJECTING. 


191 


of  the  tube  dips  beneath  the  mirrored  surface  of  the  mercury. 
If  mercury  be  now  poured  into  the  funnel-shaped  opening,  the 
knee-shaped  tube  will  become  filled  with  the  injection  fluid, 
which  soon  issues  without  air-bubbles  from  the  aperture  of  the 
metallic  tube.  The  stop-cock  is  then  to  be  closed  and  the  end 
of  the  metallic  tube  carefully  but  firmly  inserted  into  the  mouth 
of  the  canule.  The  stop-cock  should  then  be  opened  a  second 
time,  when  the  colored  fluid  will  flow  into  the  organ,  and  the 
column  of  mercury  in  the  vertical  glass  tube  will  rapidly  sink. 
This  may  be  raised,  by  a  subsequent  addition  of  the  metal,  to  an 
elevation  of  20,  30,  or  40  mm.  (in  many  organs  to  double  this  or 
more),  as  may  be  desired.  The  flowing  of  the  mercury  may 
easily  be  so  regulated,  by  means  of  the  clamp,  that  the  amount 
of  pressure  is  constantly  maintained.*  If  the  column  finally 


Fig.  78.  Hfirting's  injection  chest,  a  chest ;  c  false  bottom  for  the  injection  bottle ;  /  thermo 
meter ;  b  compartment  for  the  reception  of  the  preparation ;  d  perforated  plate,  the  position  of 
which  may  be  altered  by  means  of  the  chains  e. 

*  When  it  is  necessary  to  employ  a  very  slight  pressure  of  known  degree,  it 
is  advantageous  to  bend  the  tube  which  is  connected  with  the  funnel  four 


192  SECTION   NINTH. 

ceases  to  sink,  the  injection  may  be  discontinued  or  the  pressure 
cautiously  increased,  according  to  circumstances. 

It  is  unnecessary  to  remark  that  cold  fluids  are  here  in  place. 
It  is  preferable  to  use  a  watery  solution  of  Prussian  blue  or  the 
Richardson  mixture.  The  apparatus  just  described  may  also  be 
readily  used  for  injecting  with  gelatine  (Ludwig).  The  bottle 
is  to  be  placed  in  a  tin  chest  of  considerable  size,  which  rests  on 
feet  and  contains  a  table  for  the  support  of  the  organ  which  is 
to  be  injected.  This  chest  is  to  be  filled  with  warm  water  and 
the  temperature  maintained  by  means  of  an  alcohol  or  gas 
flame. 

A  well-adapted  arrangement  for  this  purpose,  designed  by 
Harting,  will  be  at  once  made  intelligible  to  the  reader  by  our 
fig.  78.  We  are  indebted  to  Professor  Ilering,  of  Vienna,  for 
an  excellent  apparatus  for  such  injections.  By  it  the  pressure 
on  the  fluid  may  be  accurately  measured  and  uniformly  main- 
tained. The  arrangement  is  by  no  means  simple,  so  that  we 
must  refer  to  a  description  given  of  it  by  Toldt. 

We  now  pass  to  the  consideration  of  the  method  most  exten- 
sively used,  that  of  the  syringe. 

The  small  German-silver  injection  syringes  (fig.  79,  1),  which 
may  be  bought  of  Charriere  or  Luer,  in  Paris,  for  a  few  tha- 
lers,  with  a  half-dozen  or  a  dozen  different  canules  (2,  3),  are 
sufficient  for  all  purposes,  and  will  render  equally  good  service 
for  a  number  of  years  if  used  with  some  care.  It  is  only  neces- 
sary to  carefully  smear  the  piston  from  time  to  time  with  tal- 
low, in  order  to  preserve  the  smooth,  easy  movement  which  is 
so  extremely  necessary.  It  is  also  necessary  to  clean  the  syringe 
after  being  used  for  resinous  injections  with  turpentine,  and 
after  gelatine  with  hot  or  cold  water ;  it  is  then  hung  up  by  the 
ring  of  the  piston-rod  to  permit  the  water  to  drain  away.  If,  after 
a  long  interval  of  time,  the  caoutchouc  of  the  piston  no  longer 
fits  closely,  the  syringe  is  to  be  unscrewed  and  the  piston  placed 
for  a  half  or  a  whole  day  in  cold,  or  several  minutes  in  hot  water. 
It  has  then  become  sufficiently  swollen  again,  and,  when  rubbed 

times  at  right  angles,  so  that  it  runs  downwards  and  again  upwards,  outside  the 
bottle  and  beneath  the  prolongation  of  the  level  of  the  mercury,  somewhat  ia 
the  form  of  a  manometer  (Mac-Grillavry). 


METHOD    OF   INJECTING. 


193 


with  tallow,  the  piston  performs  its  duty  anew.  Resinous 
masses  always  have  the  inconvenience  of  requiring  a  time-con- 
suming cleansing  of  the  syringe.  The  canules  should  also  be 
cleaned  with  water  after  having  been  used,  and  should  be  stood 
upon  a  warm  plate  to  dry.  Nothing  further  is  necessary  to 
keep  the  larger  tubes  open.  A  thin  silver  wire  should  always 
be  introduced  into  the  finer  and  finest  ones  after  cleaning  them, 
as,  without  this  precautionary  measure,  the  narrow  passage  is 
found  to  be  closed,  that  is,  rusted,  and  frequently  it  causes  all 
subsequent  experiments  to  remain  without  results. 


Fig.  79.  Syringe  for  Injections.  1.  a  the  tube,  with  the  projecting  edges  6  and  c  (for  conve- 
nience in  holding),  and  the  cap/,  which  is  to  be  screwed  on ;  d  piston-rod  with  the  ring  e  ;  g 
the  aperture  (mouth-piece)  of  the  syringe,  with  a  silk  thread  wound  round  it.  2  and  3.  Canulea 
of  the  finest  variety. 

Those  who  inject  much  require  several  of  these  syringes.     It 
is  also  very  convenient  to  have  a  large  syringe  of  about  double 
13 


194  SECTION    NINTH. 

the  capacity  of  the  small  instruments,  for  filling  extended  sys- 
tems of  vessels,  as  the  repeated  removal  for  filling  the  syringe  is 
always  an  unpleasant  procedure  ;  and  it  is  just  in  removing  and 
in  replacing  the  syringe  that  the  beginner  so  readily  meets  with 
a  misfortune. 

The  canules  themselves  do  not  require  any  ring-shaped  pro- 
jection, but  rather  a  notched  edge,  for  convenience  in  holding 
them.  For  frequent  work  it  is  necessary  to  have  at  least  a  dozen 
on  hand  ;  it  is  still  better  to  have  even  a  greater  stock  of  the 
most  varying  calibre,  from  about  two  mm.  aperture  to  that  of 
capillary  fineness.  I  use  those  of  German  silver  for  large  ves- 
sels ;  the  finest  are  of  sheet-iron,  and  therefore  unfortunately 
of  a  perishable  nature. 

The  remaining  contrivances  consist  of  strong,  well- waxed  silk 
thread  of  several  sorts,  several  curved  and  straight 
needles,  a  pair  of  fine  scissors,  small  ordinary  and 
curved  forceps,  also  several  slide  forceps  (or  other 
clamping  apparatus,  fig.  80)  for  possible  emergen- 
cies.    These,  together  with  ccJd  water,  are  sufficient 
for  cold  masses.     For  gelatine  injections  it  is  also 
necessary  to  have  a  kettle  with  hot  water  and  a 
double  water-bath.     The  latter  are  ordinary  deep 
copper  basins,  which  are  filled  with  warm  water 
and  kept  at  an  elevated  temperature  by  means  of  a 
spirit-lamp  burning  under  them.     They  serve  to 
receive  the   dishes   of  gelatine.     Gelatine   masses 
should  never  be  warmed  directly  over  a  fire  !     Together  with 
plates  or  porcelain  dishes,  it   is   also  convenient  to  have  an 
oblong  lead  chest  for  the  reception  of  the  organ  or  the  body  of 
the  animal  to  be  injected  warm.     The  chest  should  have  diver- 
gent walls  and  a  drain-tube  near  the  bottom,  with  a  stop-cock. 

Objects  for  injecting  are  generally  selected  from  parts  as 
fresh  as  possible — that  is,  from  animals  which  have  just  been 
killed.  I  have  frequently  used  small  animals  while  they  were 
still  warm,  directly  after  death,  which  is  preferably  induced  by 
bleeding.  In  this  way  I  have  obtained  the  best  results,  except 
where  muscular  parts  were  concerned ;  in  which  case,  espe- 
cially when  injecting  warm  masses,  the  rigor  mortis,  which  fre- 


METHOD    OF   INJECTING.  195 

quently  occurs  suddenly,  renders  the  injection  impossible. 
Very  soft  parts  may  be  previously  immersed  for  a  day  in 
alcohol,  in  order  to  render  them  harder.  By  means  of  this 
procedure  I  have  frequently  succeeded  in  injecting  the 
spleen  after  having  been  unsuccessful  with  fresh  organs,  not- 
withstanding every  precaution.  In  injecting  the  blood-vessels 
of  bodies  not  so  fresh,  the  coagulation  of  the  blood  is  a  great 
disadvantage,  which  often  ruins  the  whole  process.  It  has  been 
frequently  recommended  in  such  cases  to  precede  the  injection 
mass  with  a  stream  of  water,  and  in  certain  cases  this  procedure 
is  serviceable.  But  generally  we  soon  meet  with  numerous  ex- 
travasations, and  we  are  compelled  to  discontinue  at  an  early 
period,  long  before  a  complete  injection  has  been  accomplished. 

The  blood-vessels  of  pathological  new  formations  are  gene- 
rally difficult  to  inject.  The  walls  of  the  vessels  are  readily 
ruptured  in  consequence  of  their  extreme  delicacy.  It  is  also 
frequently  necessary  to  ligate  numerous  lateral  branches.  Cold 
transparent  masses  should  only  be  used  here,  if  anywhere.  But 
with  skill  and  perseverance  much  may  be  accomplished.  Un- 
fortunately, this  department  has  been  altogether  too  much 
neglected  by  pathological  anatomists,  with  the  exception  of 
Thiersch. 

In  order  to  inject  the  lymphatic  vessels,  for  which  purpose  all 
bodies  are  not  equally  suitable,  I  have  frequently  placed  the 
dead  body  in  water  for  a  series  of  hours,  so  that  these  vessels 
might  in  this  way  become  more  thoroughly  distended.  One 
may  also  frequently  have  the  pleasure  of  seeing  the  lymphatic 
vessels  become  well  filled,  after  having  forced  a  stream  of  water 
through  the  arteries  of  the  organ  for  some  time.  Another 
method  is  likewise  useful.  I  kill  the  animal  by  a  blow  on  the 
head  or  by  strangulation,  then  open  the  thorax,  avoiding  the 
blood-vessels,  and  ligate  the  ductus  thoracicus  high  up.  The 
body  then  remains  undisturbed  for  2-6  hours.  The  lymphatic 
vessels  are  now  sought  out;  and  are,  for  the  most  part,  found  to 
be  filled  and  distended  in  a  very  satisfactory  manner.  The  ex- 
periment may  be  made  of  ligating  the  efferent  canals  or  the 
veins  of  the  larger  glands  in  the  living  animal,  and  thus  causing 
the  lymphatic  vessels  to  become  firm  and  distended. 


196  SECTION    NINTH. 

The  freshest  possible  material  should  be  selected  for  injections 
of  the  glandular  canals.  The  canule  may  be  inserted  directly, 
or  the  passage  may  be  made  to  appear  more  distended  by  pre- 
viously forcing  water  through  the  artery,  at  the  same  time  com- 
pressing the  vein  slightly,  also  first  endeavoring  to  cause  the  se- 
cretion to  flow  out.  In  this  case  great  caution  is  always  neces- 
sary. 

In  searching  for  a  blood-vessel,  an  artery,  or  a  vein,  avoid  all 
unnecessary  cutting,  as  small  branches  may  thus  be  readily  in- 
jured, which  afterwards  makes  it  necessary  to  stop  the  rent  with 
ligatures  or  the  application  of  sliding  forceps,  and  thus  cause 
an  unpleasant  interruption  to  the  progress  of  the  work. 

In  opening  the  vessel,  which  is  best  done  under  water,  avoid 
making  the  slit  too  large,  and  above  all  do  not  make  a  transverse 
cut  on  a  small  artery,  as  in  the  introduction  of  the  canule  the 
vessel  might  readily  be  torn  in  two.  By  opening  the  vessel  un- 
der water  the  entrance  of  air,  which  is  always  to  be  carefully 
avoided  in  injecting,  is,  for  the  most  part,  prevented.  But  there 
is  still  some  air  in  the  canule  which  is  to  be  introduced.  In  or- 
der to  remove  this,  the  tube  should  be  filled  with  water  and  the 
posterior  opening  closed  with  a  cork  before  the  introduction  of 
the  canule,  a  little  precautionary  measure  wrhich,  like  so  many 
others,  apparently  unimportant,  renders  very  great  service  in 
injecting.  The  mouthpiece  of  the  syringe  should  also  be  passed 
beneath  the  surface  of  the  water,  and  then  introduced  into  the 
opening  of  the  canule. 

The  canule  having  been  successfully  introduced  into  the  ves- 
sel, it  next  becomes  necessary  to  secure  it  by  means  of  a  care- 
fully waxed  silk  thread.  The  necessary  skill  is  soon  acquired, 
the  thread  being  either  seized  with  the  forceps  and  passed  be- 
neath the  vessel,  or  brought  round  it  threaded  in  a  needle. 
Large  vessels  should  be  tied  as  firmly  as  possible ;  with  smaller 
ones  more  circumspection  is  required,  and  with  very  fine  ones, 
especially  embryonic  branches,  the  greatest  care  is  necessary. 
If  the  canule  has  a  ring-shaped  groove,  which  should  always  be 
the  case  with  large  ones,  the  ligature  is  to  be  placed  at  that 
part.  If  there  is  no  groove,  the  greatest  attention  is  to  be  paid 
to  the  application  of  the  ligature,  to  prevent  the  tube  from  slip- 


METHOD    OF   INJECTING.  197 

ping  out.  In  such  cases  the  practised  hand  of  an  assistant,  who 
places  a  finger  over  the  opening  of  the  canule  without  pressing 
the  tube  deeper  into  the  vessel,  renders  an  important  service. 

The  same  process  is  to  be  followed  in  tying  the  canules  into 
the  ducts  of  glands.  Lymphatic  vessels  require  greater  at- 
tention. That  it  is  necessary  to  inject  in  the  direction  in  which 
the  valves  open  is  self-evident ;  although,  in  a  few  cases,  the  re- 
sistance which  they  present  may  also  be  successfully  overcome. 
Still  it  is  only  rarely  and  for  special  purposes  that  this  proce- 
dure can  be  made  use  of ;  as,  for  instance,  I  succeeded  in  this 
way,  several  years  ago,  in  injecting  the  lymphatic  glands  from 
the  vas  effereus. 

It  frequently  happens,  however,  that  a  well-distended  lym- 
phatic vessel,  which  appears  very  inviting  for  injection,  can 
nevertheless  not  be  taken  advantage  of,  especially  when  the 
vessel  is  very  fine.  The  colorless  fluid  escapes  on  opening  the 
vessel,  and  frequently  the  whole  vessel  becomes  almost  unre- 
cognizable. One  is  sometimes  tormented  for  a  long  time  in  en- 
deavoring to  introduce  the  canule  within  the  collapsed  walls ; 
attempt  after  attempt  may  fail,  until  after  a  time,  in  successful 
cases,  the  desired  object  is  attained.  Coolness  and  patience  is  to 
be  recommended  to  those  who  desire  to  accomplish  anything  in 
this  direction. 

When  the  fine  lymphatic  vessels  in  the  interior  of  an  organ 
are  to  be  injected,  Ilyrtl  and  Teichmann's  puncturing  method 
is  the  process  chiefly  employed.  Ilyrtl  sometimes  makes  a 
puncture  from  the  cavity  of  a  blood-vessel  into  the  surrounding 
tissue  in  order  to  open  some  of  the  lymphatic  vessels  which  may 
be  present,  and  thus,  in  fortunate  cases,  inject  the  lymphatic 
canals  from  and  with  the  blood-vessel.  Another  way  is  to  make 
a  small  opening  directly  into  the  tissue,  in  order  to  inject  imme- 
diately from  this  into  any  of  the  lymphatic  vessels  which  may 
have  been  opened,  and  from  these  into  larger  systems. 

This  may  be  accomplished  in  two  ways.  With  larger  canules, 
a  needle  may  be  passed  through  the  tube ;  after  having  inserted 
the  canule  into  a  small  opening  in  the  tissue,  the  needle  may  be 
pressed  forward  and  the  tube  made  to  follow  till  the  desired 
point  is  reached,  when  the  needle  is  to  be  withdrawn. 


198  SECTION   NINTH. 

Where  the  walls  were  very  thin,  I  have  had  better  success  by 
another  method.  A  small  puncture  is  to  be  made  with  a  fine 
cataract-needle  or  the  point  of  a  fine  scissors  which  has  been 
dipped  into  the  injection  fluid.  The  tube  is  now  to  be  passed 
into  the  small  opening,  recognizable  by  the  little  point  of  color, 
and  very  slowly  and  carefully  pushed  forward  with  an  easy 
rotating  movement.  When  one  has  the  requisite  practice  and 
patience  for  this  process,  lymphatics  may  be  injected  even 
where  the  method  of  preceding  the  canule  with  the  pricking 
instrument  would  fail.  Nevertheless,  it  always  remains  a  diffi- 
cult piece  of  work — as,  for  instance,  in  the  small  intestines  of 
the  Guinea-pig — to  guide  the  tube  along  in  the  submucous  tis- 
sue, as  the  slightest  awkwardness  in  the  movement  causes  a 
perforation  of  the  mucous  membrane.  Many  attempts  will 
fail,  till  at  length,  by  a  lucky  hit,  the  injection  succeeds.  All 
who  desire  to  accomplish  anything  in  this  direction  should  first 
practise  on  organs  which  are  easy  to  inject,  of  which,  fortu- 
nately, there  are  many.  Try,  for  instance,  the  vermiform  pro- 
cess of  the  rabbit,  in  which  the  injection  is  very  easy ;  then  the 
small  intestine  of  the  sheep,  the  testicle  of  the  calf,  and  the 
Peyer's  glands  of  the  last-named  animal,  and  proceed  gradually 
to  more  difficult  organs.  In  many  cases  it  is  unnecessary  to  tie 
the  canule,  as  compression  may  often  be  better  made  with  the 
fingers  or  fine  sliding  forceps.  If  a  ligature  be  used,  a  very 
fine  needle  should  be  employed,  and  the  loop  should  be  tight- 
ened with  the  greatest  precaution,  as  very  frequently  the  point 
of  the  canule  is  finally  thrust  through  the  walls  of  the  vessel. 
Punctures  which  are  too  large  permit  the  escape  of  the  injec- 
tion fluid.  Teichinann,  who  has  obtained  great  experience 
in  this  direction,  very  properly  remarks  that  a  puncture 
made  at  random  is  not  sufficient,  but  that  it  is  to  be  made 
in  a  direction  where  fine  lymphatic  vessels  are  supposed  to 
be.  If  the  extravasation  which  forms  at  the  commencement 
remains  small,  the  injection  frequently  succeeds.  If  it  is 
large  at  the  very  beginning,  and  increases  rapidly,  stop,  for 
the  procedure  has  failed.  If  a  rapidly-increasing  extravasa- 
tion subsequently  takes  place,  it  is  likewise  necessary  to  dis- 
continue at  once.  Yery  cautious  management  of  the  syringe 


METHOD    OF   INJECTING.  199 

is  for  the  most  part  necessary,  especially  at  the  commence- 
ment of  the  injection. 

But  we  have  wandered  from  our  subject.  When  the  tube 
has  been  firmly  secured  in  position,  the  syringe  is  to  be  thor- 
oughly filled  from  beneath  the  surface  of  the  injection  fluid; 
and  while  the  canule,  which  is  now  opened,  is  seized  and  some- 
what raised  by  the  index  and  middle  fingers  of  the  left  hand, 
the  mouthpiece  of  the  syringe  is  to  be  inserted  as  deeply  as 
possible.  The  syringe  is  to  be  held  by  the  middle  phalanges  of 
the  index  and  middle  fingers  of  the  right  hand,  and  the  thumb 
is  placed  in  the  ring  of  the  instrument.  It  is  important  that 
the  forearm  should,  at  the  same  time,  rest  quietly  and  conve- 
niently on  the  table. 

In  this  manner,  therefore,  the  injection  of  the  mass  com- 
mences :  two  fingers  of  the  left  hand  holding  the  canule,  three 
of  the  right  the  syringe,  the  piston  being  pressed  forwards  as 
slowly  as  possible  and  with  the  utmost  steadiness.  Every 
awkward,  spasmodic  impulse  is  to  be  avoided,  especially  to- 
wards the  end  of  an  injection.  If  the  work  succeeds,  the 
colored  mass  is  seen  to  move  forward  in  the  vascular  system, 
and  it  is  noticed  how  in  some  places  the  capillary  systems  be- 
come filled,  how  these  latter  places  constantly  become  more 
numerous,  and  at  the  same  time  increase  at  the  periphery  until 
they  fiow  together.  During  this,  the  finger  feels  a  gradually 
increasing  pressure,  and  one  soon  learns  to  accommodate  the 
motion  of  the  piston  to  it.  If  two  or  three  additional  syringe- 
f uls  of  the  mass  be  necessary,  the  syringe  is  to  be  removed, 
preferably  before  it  is  entirely  emptied,  arid  the  opening  of  the 
canule  closed  with  the  thumb  of  the  left  hand.  The  syringe  is 
to  be  refilled  either  by  the  operator,  with  his  right  hand,  or  by 
an  assistant.  If  one  possesses  several  syringes  furnished  with 
similar  mouthpieces,  it  is  well,  when  injecting  large  organs 
with  cold  masses,  to  have  several  of  them  lying  filled  near  him 
at  the  very  commencement,  so  as  to  instantly  exchange  the 
emptied  syringe  for  one  that  is  filled. 

When  the  injection  is  completed,  whereby  it  is  often  well  to 
ligate  the  opposite  vessel  in  order  to  prevent  an  escape  of  the 
fluid,  the  canule  is  to  be  closed  by  means  of  a  stopper  of  cork, 


200  SECTION    NINTH. 

or  better  of  metal,  fitted  into  its  opening,  or  by  means  of  the 
above  mentioned  (p.  189)  short  tube  with  a  stop-cock.  The 
injected  vessel  is  now  tied  further  below,  and  the  other  liga- 
ture which  holds  the  canule  is  finally  removed,  so  that  the  tube 
may  be  taken  out. 

Although  the  above-mentioned  manipulations  are  soon 
learned  with  a  little  aptness,  it  is  difficult  to  properly  estimate 
the  moment  when  the  injection  must  be  discontinued.  Here 
the  beginner  very  readily  errs,  and  even  the  most  practised  now 
and  then  has  his  unlucky  day.  Too  little  may  be  done ;  the 
injection  is  then  insufficient,  only  small  places  are  filled,  or  fine 
capillary  systems  even  not  at  all.  Inversely,  an  injection  push- 
ed too  far  leads  to  extravasations,  and  finally  to  an  unserviceable 
preparation.  If  it  be  noticed  that  numerous  though  at  first 
small  extravasations  form,  desist,  or  they  will  be  seen  to  increase 
in  a  frightful  measure.  That  a  considerable  escape  of  the  in- 
jection fluid  requires  an  instant  cessation  in  order  to  rescue 
what  is  possible,  is  self-evident.  If  Beale's  cold  mixture  be 
employed,  towards  the  end  of  the  injection  the  colorless  fluid 
is  seen  to  be  pressed  through  the  walls  of  the  urinary  canals 
and  the  envelope  of  the  organ,  appearing  on  the  surface  as  a 
fatty,  glistening  moisture.  Then  is  the  time  to  leave  off;  it 
would  be  too  soon  in  most  cases  before  this  exudation  takes 
place. 

The  double  injection  is  naturally  much  more  difficult  than 
the  single ;  firstly,  on  account  of  the  entire  procedure,  and  then 
while  too  much  should  not  be  sent  through  one  system,  that  of 
the  vein,  for  instance,  in  order  that  the  possibility  may  remain 
for  the  one  injection  to  meet  that  from  the  second  system  in  the 
capillaries.  For  injecting  arteries  and  veins,  such  masses  should 
always  be  used,  if  possible,  which  give  a  pleasant  blending  of 
colors  when  they  meet ;  for  example,  Prussian  blue  and  car- 
mine, Prussian  blue  and  white,  while  yellow  and  green  appear 
less  handsome  to  the  eye.  Masses  which  flow  when  warm  and 
harden  when  cooled  generally  deserve  the  preference  for  these 
cases,  and  with  gelatine  masses  I  usually  allow  some  time  to 
elapse  between  the  first  and  second  injection,  so  that  the  former 
may  at  least  acquire  some  firmness.  For  most  cases,  the  vein 


METHOD    OF    INJECTING.  201 

may  be  first  injected  and  then  tied  in  the  usual  way.  After- 
wards, if  there  be  considerable  resistance,  the  artery  with  its 
ramifications  are  to  be  injected. 

For  many  organs,  as  for  instance  the  eye,  or  the  spleen,  it  is 
well  to  drive  the  injection  mixture  intended  for  the  venous 
system  through  the  artery  first,  and  then,  through  the  same 
vessel,  the  second  mass  which  is  to  serve  for  the  arterial  system. 
Not  unfrequently  the  injection  may  be  essentially  regulated  by 
keeping  open  or  closing  the  terminal  vein. 

If,  together  with  the  blood-vessels,  it  be  also  intended  to 
inject  the  lymphatics,  or,  in  a  glandular  organ,  its  system  of 
canals,  the  blood-vessel  may  either  be  injected  first  and  then 
the  latter,  or  inversely.  If  the  lymphatics  are  to  be  injected  by 
the  puncturing  method,  avoid  injuring  the  injected  blood-ves- 
sels as  far  as  possible. 

For  all  injections  of  the  glandular  passages  and  the  lymphatics, 
transparent  cold  mixtures  deserve  the  preference,  as  was  already 
remarked,  on  account  of  their  ready  permeability,  as  well  as  in 
consequence  of  the  less  degree  of  injury  which  their  employ- 
ment exerts  on  the  tissues. 

Although  the  directions  given  are  in  no  wise  to  be  regarded 
as  complete,  and  require  special  modifications  for  special  organs, 
which  are  only  to  be  obtained  by  experiment,  they  will,  never- 
theless, considerably  facilitate  the  labors  of  the  begin  ner. 

A  successful  injection  having  been  made,  the  further  question 
now  arises  :  What  is  to  be  done  with  the  specimen  in  order  to 
prepare  it  for  examination  ?  . 

As  was  above  remarked,  warm  injections  require,  bey  on  1  all 
things,  the  necessary  time  for  the  mass  to  harden.  Resinous 
substances  require  a  longer  time  than  gelatine.  With  Beale's 
cold  mixture,  the  objects  may  be  used  at  once ;  with  Ilyrtl's 
ether  injection,  the  injected  organ  may  be  used  after  a  quarter 
of  an  hour. 

When  a  specimen  has  been  injected  with  a  gelatine  mass,  it 
should  without  delay,  or  at  most  only  sufficient  to  wash  off  its 
surface,  be  placed  in  ice-water  (in  winter,  snow),  and  left  till 
the  mass  has  become  hardened.  This  may  be  readily  recognized 
when  the  contents  of  the  larger  vessels  no  longer  yield  when 


202  SECTION    NINTH. 

felt  with  the  points  of  the  fingers.  The  injected  organ  is  placed, 
for  further  hardening  and  preservation,  in  weak,  and  then  in 
stronger  alcohol.  It  is  well  to  let  it  lie  quietly  in  this  for  several 
days  before  proceeding  further.  It  is  better  to  place  very  sen- 
sitive objects,  directly  after  the  injection,  in  alcohol  which  has 
been  previously  placed  in  ice,  or  which  has  been  cooled  by  put- 
ting pieces  of  ice  in  it  (Thiersch).  A  few  drops  of  acetic  acid 
are  to  be  added  to  the  alcohol  for  injections  with  Prussian  blue. 

Naturally,  even  here,  numerous  modifications  are  necessary  in 
certain  cases.  Thus  smaller  organs  may  be  left  in  the  alcohol 
without  cutting  them,  as  also  groups  of  organs  and  the  entire 
bodies  of  the  smaller  mammalia,  which  may  be  prepared  after 
a  few  days.  It  is  preferable  to  open  an  intestinal  canal,  which 
has  been  injected  with  gelatine,  after  the  injection  fluid  has 
hardened.  This  should  be  done  in  water,  and  the  canal  washed 
out  carefully.  Portions  of  intestine  with  the  lymphatics  in- 
jected I  cut  open,  and  run  a  stream  of  water  through  the  canal 
to  \vash  out  its  contents,  and  then  place  the  preparation  for  a 
day  or  more  in  alcohol.  Large  organs  after  being  immersed  in 
alcohol,  for  example,  the  kidney  of  one  of  our  ruminata,  should 
be  cut  open  on  the  following  day  at  furthest,  lest  the  cortex 
should  harden  while  the  internal  portion  decomposes.  Immer- 
sion in  chromic  acid  solutions  is  also  applicable  to  such  pur- 
poses, Prussian  blue  being  well  preserved  in  them ;  but  it  is 
rare  that  alcohol  can  be  altogether  dispensed  with.  I  also  place 
organs  injected  with  Beale's  mixture,  almost  without  exception, 
in  alcohol,  in  order  to  obtain  the  necessary  hardening  of  the 
tissue. 

After  a  few  days,  when  the  preparation  has  acquired  the 
necessary  firmness,  it  may  be  examined  by  the  ordinary  meth- 
ods already  given.  Thin  horizontal  and  vertical  sections,  for 
example,  are  to  be  freed  from  particles  of  coloring  matter 
which  have  escaped  by  washing,  or,  still  better,  by  means  of  a 
camel's-hair  pencil.  They  are  then  to  be  reviewed  with  the 
microscope,  and,  if  it  be  desired  to  preserve  them  permanently, 
they  are  to  receive  such  further  treatment  as  may  be  necessary. 

The  old  method  of  mounting  dry  is  to  be  recommended  wrhen 
the  preparation  is  to  be  used  as  an  opaque  object.  It  is  still 


METHOD    OF    INJECTING.  203 

better  to  mount  it  carefully  in  Canada  balsam,  which  will  be 
treated  of  in  the  following  section. 

Glycerine  is  being  more  and  more  employed  for  mounting 
histological  preparations,  and,  as  may  be  readily  conceived,  it 
reproduces  the  natural  relations,  although  connected  with  the 
very  great  disadvantage  of  being  much  less  durable. 

For  the  preservation  of  injected  organs  for  a  considerable 
length  of  time,  alcohol,  weak  or  strong,  according  to  circum- 
stances, is  used. 


Section 


THE  MOUNTING  AND  ARRANGEMENT  OF  MICROSCOPIC 
OBJECTS. 

THE  reader  will  have  perceived  from  the  preceding  sections 
that  it  is  by  no  means  one  of  the  simplest  and  easiest  things  to 
obtain  useful  microscopic  specimens,  even  if,  at  the  same  time, 
we  also  disregard  the  rareness  of  many,  as,  for  instance,  those 
of  embryonic  and  pathological  occurrences.  The  desire  to  pre- 
serve for  the  longest  possible  time  such  objects  as  are  only 
obtained  with  trouble  or  the  concurrence  of  fortunate  circum- 
stances is  also  sufficiently  obvious ;  and,  in  fact,  the  effort  to 
obtain  such  preparations  is  as  old  as  microscopy  itself.  The 
value  of  such  collections  is  quite  as  great  for  the  study  of  this 
branch  of  natural  science  as  for  that  of  others. 

Commencing  with  crude  attempts  in  the  preservation  of  hard 
structures,  dried  preparations  of  injections,  etc.,  the  industry  of 
the  investigators  has  gradually  brought  better  and  better  meth- 
ods to  light,  so  that  this  now  constitutes  an  important  section  of 
microscopic  technology.  At  the  same  time,  although  much  has 
been  accomplished  in  this  department,  still  more  remains  to  be 
attained  and  explored ;  most  of  those  branches  relating  to  pre- 
serving being  at  the  present  day  still  in  an  incipient  condition. 

Many  portions  of  the  body  may  be  sufficiently  well  preserved 
in  ordinary  alcohol  for  the  purpose  of  having  at  hand  material 
from  which,  in  case  of  necessity,  a  serviceable  preparation  may 
be  made  with  rapidity  and  little  trouble.  Hardened  glands, 
intestines,  the  central  portions  of  the  nervous  system,  tumors, 
injections  with  gelatine  and  cold  masses,  such  as  have  been  de- 
scribed in  the  previous  section,  and  embryos,  may  be  preserved 
in  the  most  convenient  manner  in  well-closing  glass  bottles,  and 
constitute,  especially  for  a  teacher,  invaluable  material  for  in- 
struction. 


ETC.  205 

But,  in  most  cases,  the  matter  is  not  so  simple  when  a  definite 
microscopic  preparation  is  to  be  preserved.  For  this  purpose 
certain  methods  are  necessary. 

Hard  structures  of  many  kinds,  especially  those  of  a  trans- 
parent nature,  scales  of  diatomes,  thin  sections  of  bone  and  teeth, 
and  crystals,  may  be  permanently  preserved  in  a  very  simple 
way  if  they  are  placed  on  a  slide  and  covered  with  a  thin  cover- 
ing glass,  and  the  latter  fastened  to  the  former.  Various  sub- 
stances may  be  used  for  this  purpose ;  as,  thick  gum-arabic  (a 
solution  of  gum  with  powdered  starch  is  good),  wax,  resinous 
substances  of  thick  consistence,  and  Canada  balsam.  For  the 
protection  of  the  fragile  covering  glass,  the  whole  may  after- 
wards be  covered  with  colored  paper,  through  which  an  aperture 
has  been  made  with  a  punch.  It  is  well  for  those  who  work 
much  with  such  objects  to  have  lithographed  covers  prepared, 
the  posterior  surfaces  of  which  are  gummed  for  the  sake  of 
economizing  time.  On  one  surface  of  the  slide  the  paper  should 
project  beyond  its  edges  in  such  a  manner  that  they  may  be 
covered  by  it,  while  the  other  siirface  of  the  glass  plate  requires 
a  smaller  covering.  One  soon  acquires  the  little  dexterity 
necessary  to  apply  these  covers.  The  gummed  surface  should 
only  be  slightly  moistened,  so  that  when  pressed  on  to  the  slide 
the  gum  will  not  exude  and  flow  over  the  visible  portion  of  the 
preparation.  Very  many  such  preparations,  which  are  in  circu- 
lation and  to  be  purchased,  may  be  recommended  as  models ; 
as,  for  instance,  those  of  Bourgogne,  in  Paris ;  Moller,  in  Wedel 
(Ilolstein) ;  and  Rodig,  in  Hamburg. 

But,  as  we  have  already  remarked,  only  a  small  number  of 
objects,  which  are  transparent^/*  se^  permit  of  this  most  simple 
method  of  treatment.  The  greater  portion  of  those  which  are 
to  be  preserved  dry  require,  in  order  to  render  them  transparent, 
to  be  mounted  in  a  substance  which  refracts  the  light  strongly, 
in  a  gradually  hardening  resinous  material. 

For  this  purpose  there  is  none  more  important  or  more 
generally  used  than  the  Canada  balsam,  and,  indeed,  it  suffices 
for  all  cases.  Other  resinous  substances,  such  as  copal  lack, 
damar  varnish,  and  mastic  are  really  superfluous,  and  are,  at 
most,  only  to  be  used  here  and  there  by  way  of  experiment. 


206  SECTION   TENTH. 

Several  so^ts  of  Canada  balsam  occur  in  commerce.  To  be 
good  it  should  be  of  thick  consistence,  nearly  colorless,  and 
thoroughly  transparent.  It  is  to  be  kept  in  wide-mouthed  ves- 
sels closed  with  glass  stoppers,  in  order  to  limit  as  much  as  pos- 
sible its  tendency  to  harden  in  the  air.  If,  in  consequence  of 
the  prolonged  action  of  the  air,  it  has  become  much  hardened 
it  may  be  thinned,  after  being  moderately  warmed,  with  oil  of 
turpentine,  or,  which  is  less  preferable,  with  a  little  chloro- 
form. 

The  preparation  to  be  mounted  must  be  thoroughly  dry. 
Hence,  in  many  cases  a  preparatory  drying  process  will  be  ne- 
cessary. For  this  purpose  the  preparation  may  be  placed  over 
a  water-bath,  or  over  sulphuric  acid  or  chloride  of  calcium. 
Many  preparations  may  be  advantageously  placed  in  oil  of  tur- 
pentine, in  which  they  are  to  be  left  for  at  least  a  few  minutes. 
If  the  specimen  to  be  mounted  contains  air,  a  longer  immersion 
in  turpentine,  occasionally  in  that  which  is  warmed,  will  be  ne- 
cessary. 

The  preparation  should  be  mounted  in  the  following  manner. 
The  dry,  cleanly-washed  slide  is  to  be  moderately  warmed  over 
the  spirit-lamp,  but  never  to  an  extreme  degree.  A  drop  of 
the  balsam  is  then  to  be  taken  from  the  bottle  by  means  of  a 
pointed  glass  rod  and  placed  on  the  slide.  It  will  then  spread 
out  into  a  layer  which,  in  fortunate  cases,  will  be  quite  homo- 
geneous and  contain  no  air-bubbles.  But  if  any  of  the  latter 
remain  in  the  stratum  of  balsam  (if  the  slide  be  too  warm  they 
are  developed  by  the  boiling  of  the  balsam),  they  are  made  to 
burst  by  touching  them  with  the  point  of  a  heated  needle,  or 
are  brought  to  the  edge  of  the  layer  of  balsam  with  the  point  of 
a  cold  needle.  The  object  to  be  mounted  is  now  placed  in  posi- 
tion, and  a  second  drop  of  balsam  is  placed  over  it  by  means  of 
the  glass  rod.  The  two  layers  of  balsam  will  soon  How  together 
if  the  procedure  be  rapid  or  the  slide  be  again  slightly  warmed. 
The  clean  and  moderately  warmed  covering  glass  is  now  to  be 
seized  with  the  forceps  and  placed  in  an  inclined  position,  with 
the  side  opposite  the  forceps  lowest,  over  the  layer  of  balsam, 
and  then  allowed  to  gradually  assume  a  horizontal  position  till 
it  completely  covers  the  object.  If  there  be  any  air-bubbles 


THE   MOUNTING,    ETC.  207 

still  remaining,  they  may  be  driven  to  the  margin  of  the  cover- 
ing glass  by  careful  pressure  on  its  other  edge,  provided  the 
mounted  object  be  of  a  nature  which  permits  of  the  necessary 
pressure.  The  preparation  is  now  to  be  reviewed  with  the  aid 
of  a  low  power.  If  several  air-bubbles  are  still  to  be  discovered, 
it  is  preferable  to  place  the  slide  on  a  warm  body  (in  winter  it 
is  best  to  place  it  on  the  cover  of  an  earthenware  stove)  covered 
with  a  bell-glass,  and  left  for  several  hours,  whereby,  at  the 
same  time,  the  balsam  hardens  more  rapidly,  and  on  this  account 
it  is  an  advantageous  procedure,  even  where  there  are  no  air- 
bubbles. 

If  too  much  Canada  balsam  has  been  used,  a  quantity  of  it 
usually  spreads  beyond  the  edge  of  the  covering  glass,  or  even 
on  to  its  surface.  In  such  cases  it  is  necessary  to  wait  till  the 
balsam  hardens,  after  which  it  may  be  scratched  off  with  a 
knife-blade,  and  the  surface  of  the  glass  cleaned  with  a  rag 
freshly  moistened  with  oil  of  turpentine  or  benzine. 

The  hardening  of  the  balsam  at  the  interior  of  the  prepara- 
tion proceeds  very  slowly,  so  that  it  still  remains  fluid  for  days, 
and  even  weeks,  while  the  edges  have  become  hard.  By  an 
awkward  manipulation  the  covering  glass  may  be  displaced 
and  the  preparation  ruined. 

Occasionally  a  Canada  balsam  is  met  with  which  is  at  first  of 
a  somewhat  more  fluid  consistence.  In  this  case  the  mounting 
may  be  done  on  a  cold  slide,  which  always  economizes  a  certain 
amount  of  time.  Such  preparations  should  always  be  placed  for 
a  time  on  a  slightly  warmed  support,  so  as  to  dry  more  rapidly. 
Although  it  is  quite  necessary  to  accomplish  the  expulsion  of 
the  air-bubbles  from  most  specimens  mounted  in  Canada  bal- 
sam, there  are  other  objects  in  which  the  air  contained  in  the 
finest  canals  is  of  importance  for  the  recognition  of  certain 
structural  peculiarities,  and  the  air  must  therefore  be  retained. 
If,  for  -example,  we  place  a  section  of  bone  directly,  or  after 
having  been  in  turpentine,  into  Canada  balsam  which  is  very 
fluid,  the  canaliculi  and  the  cavities  of  the  bone  become  filled 
with  this  medium,  which  gradually  penetrates  in  all  directions 
and  forces  out  the  air.  But  the  processes  of  the  bone  corpus- 
cles and  the  canaliculi  appear  distinct  only  when  they  contain 


208  SECTION   TENTH. 

air,  and  it  is  only  in  this  way  that  the  bone  presents  a  charac- 
teristically elegant  appearance. 

Such  preparations  must  be  mounted  warm  with  the  thickest 
possible  Canada  balsam.  For  this  purpose  the  balsam  may  be 
placed  in  an  open  vessel  in  a  warm  place,  and  covered  with  a 
bell-glass  until  it  becomes  quite  hard  and  firm.  It  is  unneces- 
sary to  remark  that  previous  immersion  of  the  object  in  oil  of 
turpentine  is  here  to  be  avoided,  and  that  in  mounting  it  is 
necessary  to  expose  the  Canada  balsam,  slide,  and  cover  to  a 
considerably  elevated  temperature. 

Frequently — especially  with  histological  work — when  it  is 
desired  to  mount  a  very  thin  and  delicate  specimen,  as  the 
object  is  warmed  it  will  be  seen,  to  one's  great  vexation,  to 
shrink,  become  curved,  and  finally  break.  Here  a  solution  of 
Canada  balsam  in  ether,  or,  still  better,  in  chloroform,  filtered 
through  ordinary  filtering  paper,  is  in  place  ;  it  may  be  diluted 
according  to  circumstances.  By  means  of  a  brush  or  a  glass 
rod  it  is  placed  cold  on  the  slide,  the  object  is  placed  in  this, 
then  more  fluid  is  added,  and  finally  the  covering  glass  is  laid 
on.  As  the  dissolving  medium  evaporates,  the  air  generally 
enters  on  one  side  between  the  plates  of  glass.  In  such  cases 
the  preparation  is  to  be  held  in  a  slanting  position,  and  a  few 
drops  more  of  the  solution  added  until  the  process  of  mounting 
is  finally  completed.  The  whole  procedure,  which  may  also  be 
employed  for  more  substantial  objects,  is  very  convenient  and 
cleanly. 

But  how  should  one  proceed  when  one  of  the  soft  watery 
tissues,  such  as  the  greater  portion  of  our  body  presents,  is  to 
be  placed  in  Canada  balsam?  How  are  injected  preparations 
to  be  treated  ? 

That  this  can  only  be  accomplished  by  intermediate  pro- 
cesses is  self-evident.  That  is,  the  water  must  be  expelled  by  a 
fluid  which  mixes  with  it ;  this  is  to  be  replaced  by  another, 
etc.,  until  at  last  the  Canada  balsam  may  be  used  for  the  final 
saturation. 

Suppose  we  have  a  thin  section  of  the  spinal  cord,  kidney, 
or  spleen,  which  has  been  tinged  with  carmine  or  some  other 
coloring  material,  or  the  section  of  an  intestine,  brain,  or 


THE    MOUNTING,    ETC.  209 

lymphatic  gland,  with  the  blood-vessels  and  lymphatics  injected, 
and  we  desire  to  mount  the  same  as  a  dry  preparation,  but  at 
the  same  time  to  avoid  the  shrinking  occasioned  by  simple 
drying,  which  would  change  the  preparation,  in  fortunate 
cases,  to  a  caricature,  or,  in  less  fortunate  ones,  to  hiero- 
glyphics. The  object  is  to  be  placed  for  a  day  in  very  strong, 
or  better,  in  absolute  alcohol;  from  this  it  is  transferred  to 
strong  methylated  alcohol  for  half  an  hour,  although  this 
intermediate  step  may  also  be  dispensed  with.  By  this  means 
the  water  has  been  removed  and  the  alcohol  has  taken  its  place. 
The  preparation  is  now  to  be  removed  from  the  alcohol, 
preferably  by  means  of  a  filter,  and  just  as  it  begins  to  dry  it 
is  placed  in  oil  of  turpentine.  The  previously  mentioned 
small,  flat  glass  boxes  are  very  suitable  for  this  purpose. 
Sometimes  the  process  of  becoming  transparent  can  be  very 
conveniently  followed  under  the  microscope.  Then,  by  placing 
a  thick  plate  of  glass  which  just  covers  the  preparation  over  it, 
it  will  be  pressed  against  the  flat  bottom  of  the  vessel,  and  all 
curving  of  the  object  will  be  prevented,  and  the  shrinking  will 
be  limited  to  a  considerable  degree,  even  though  the  specimen 
remains  in  the  oil  of  turpentine  for  several  days.  After 
several  hours,  all  the  alcohol  is  expelled  by  the  turpentine, 
and  the  object  is  ready  for  mounting  in  the  chloroform  solution 
of  Canada  balsam.  Excellent  preparations  may  thus  be 
obtained  when  one  has  once  mastered  this  method.  All 
injected  specimens  (those  with  nitrate  of  silver  also)  should 
be  mounted  diy  in  this  way  only.  In  the  same  manner  many 
histological  details,  even  cylindrical  epithelium  and  other 
delicate  cells,  may  be  preserved  so  as  to  be  risible,  and  if 
carefully  tinged  with  carmine  or  blue,  they  may  be  rendered 
still  more  distinct.  All  the  transparent  colors  which  were 
mentioned  as  suitable  for  combination  with  gelatine  are  well 
preserved  in  this  way.  At  the  same  time  we  would  also  add,  as 
a  precautionary  rule,  to  add  a  drop  of  glacial  acetic  acid  to  the 
alcohol  used  for  drawing  the  water  out  of  preparations  injected 
with  Prussian  blue. 

We  would  here  add  still  another  little  precautionary  measure. 

It  is  best  to  allow  very  thin  and  delicate  sections  to  become 
•H 


210  SECTION    TENTH. 

sufficiently  dry  on  the  filter,  then  to  cut  out  the  portion  of 
paper  on  which  the  object  rests  and  immerse  it  in  oil  of 
turpentine.  By  a  slight  movement  the  preparation  may  then 
be  floated  off  from  the  paper. 

We  have  placed  this  procedure,  with  all  its  minutiae,  before 
the  reader,  because  of  its  great  importance. 

Here,  as  everywhere,  the  greatest  cleanliness,  the  use  of 
filtered  fluids,  etc.,  is  necessary. 

Thiersch  has  quite  recently  made  use  of  colophony  for  mount- 
ing such  preparations.  lie  prepares  it  in  the  following  manner : 
— It  is  best  for  the  microscopist  to  prepare  the  colophony  him- 
self, and  a  solution  of  it  in  absolute  alcohol  of  syrupy  consistence 
should  be  used.  The  advantage  which  this  material  presents  is, 
that  the  preparation  may  be  placed  in  it  directly  from  the  abso- 
lute alcohol,  without  becoming  cloudy  and  without  prejudice  to 
the  durability  of  the  specimen.  Venetian  turpentine  is  to  be 
dissolved  in  an  equal  volume  of  sulphuric  ether,  and  the  solu- 
tion filtered  through  paper.  The  ether  and  oil  of  turpentine  are 
then  to  be  expelled  by  the  heat  of  a  moderate  fire,  till  the  resi- 
duum shows  a  shell-like  fracture  when  cold. 

But  the  natural  condition  of  the  tissues  is  completely  repre- 
sented only  when  mounted  in  a  moist  condition.  This  method 
permits  of  the  most  accurate  recognition  of  delicate  textural 
relations,  pale  cells  and  fibres,  etc.,  and  should  not  be  omitted 
with  any  tissue  in  the  production  of  histological  collections,  as, 
even  in  cases  where  good  dry  preparations  can  be  obtained,  it 
affords  an  instructive  comparison. 

Among  all  the  preservative  fluids  for  animal  soft  parts  there 
is  none  which  stands  higher,  at  the  present  time,  than  glycerine. 
Its  strong  refractive  power,  its  property  of  combining  with 
water  and  of  attracting  the  same  from  the  atmosphere,  render 
it  an  invaluable  medium  for  moimtinsr  animal  tissues  containing: 

O  C3 

water.  It  may  be  truly  said,  that  what  Canada  balsam  is  to 
dry  tissues  glycerine  is  to  moist  ones. 

The  ordinary  impure  glycerine  may  be  used  in  the  prepara- 
tion of  a  temporary  specimen,  for  brushing,  etc.,  but  not,  how  • 
ever,  for  permanent  preparations.  Here  the  purified  glycerine, 
containing  no  lead  and  as  little  water  as  possible,  is  always  to  be 


THE   MOUNTING,    ETC.  211 

used.  Undiluted,  it  renders  the  preparation  very  transparent ; 
occasionally,  after  a  time,  too  much  so.  For  many  objects  it 
must,  therefore,  be  diluted  with  distilled  or  camphor  water 
in  about  equal  proportions,  more  or  less,  according  to  circum- 
stances. It  is  very  useful,  indeed  almost  indispensable,  to  wash 
the  preparations  which  are  to  be  permanently  mounted  for 
several  days  in  pure  glycerine,  or  a  mixture  of  glycerine  and 
water,  in  a  small  vessel,  whereby  the  degree  of  transparency 
which  they  will  assume  may  be  ascertained  at  the  same  time. 

The  preparation  is  then  to  be  mounted  in  the  ordinary  man- 
ner by  means  of  one  of  the  cements  hereafter  mentioned.  The 
superfluous  glycerine,  which  spreads  beyond  the  covering  glass, 
may  be  removed  with  a  fine  pipette  and  dried  with  a  cloth 
moistened  in  alcohol.  The  nature  of  glycerine  is  such  as  to 
render  it  unnecessary  to  be  in  haste  in  the  application  of  the 
cement,  so  that  a  number  of  specimens  may  be  allowed  to  ac- 
cumulate before  it  is  laid  on  to  the  borders. 

For  many  purposes  I  have  found  it  well  to  add  two  drops  of 
strong  muriatic  acid  to  the  ounce  of  glycerine.  Objects  injected 
with  carmine  or  Prussian  blue  always  require  this  addition, 
otherwise  the  color  will  fade  and  disappear  after  a  time. 
Acetic  acid  accomplishes  the  same  purpose,  and  possibly 
better.  Ranvier  has  recently  proposed  the  combination  with 
formic  acid  (1 :100). 

As  glycerine  is  a  constituent  of  many  mixtures,  so  also  may 
many  other  materials  be  added  to  it,  and  thus  produce  more 
complicated  mounting  fluids.  Thus,  for  example,  gelatine,  gum- 
arabic,  etc.,  may  be  combined  with  the  glycerine. 

Deane  recommends  a  mixture  of  glycerine  4  ounces,  distilled 
water  2  ounces,  and  gelatine  1  ounce.  The  latter  is  to  be  first 
dissolved  in  the  water  and  the  glycerine  then  added.  I  have 
had  no  experience  with  tannin  and  glycerine. 

Beale  also  recommends  one  of  these  combinations  of  glyce- 
rine with  gelatine.  A  certain  quantity  of  pure  gelatine  is  al- 
lowed to  soak  in  water  until  it  swells  up  and  becomes  soft.  It 
is  then  placed  in  a  glass  vessel  and  melted  by  the  heat  of  boiling 
water  (that  is,  on  a  water-bath).  To  this  fluid  an  equal  quantity 
of  strong  glycerine  is  added  and  filtered  through  flannel.  The 


212  SECTION   TENTH. 

mixture  may  be  kept  for  any  length  of  time,  and  only  requires 
to  be  slightly  warmed  before  being  used.  Klebs  employs  2 
parts  of  a  concentrated  solution  of  isinglass  and  1  part  of  pure 
glycerine  slightly  warmed. 

Bastian  recommends  a  mixture  of  15  parts  of  glycerine  and 
1  part  of  carbolic  acid  for  mounting  tissues  not  tinged. 

Farrants  employs  a  still  more  complicated  mixture,  consist- 
ing of  equal  parts  of  gum-arabic,  glycerine,  and  a  saturated  solu- 
tion of  arsenious  acid.  The  mixture  is  to  be  used  in  the  same 
way  as  the  Canada  balsam. 

Although  glycerine  is  the  most  important  preservative  fluid 
now  known,  answering  all  the  requirements  for  many  animal 
tissues,  nevertheless  one  should  not  believe  that  everything 
can  be  preserved  in  it  with  success.  Delicate,  fresh  watery 
tissues,  for  example,  blood-corpuscles  or  ganglion  cells,  soon 
lose  a  portion  of  their  water  and  become  distorted.  The 
strong  refractive  power  of  glycerine  is,  therefore,  a  disadvan- 
tage for  transparent  tissues,  however  excellent  it  may  appear  to 
be  for  those  which  are  hardened.  Besides  glycerine,  a  whole 
series  of  preservative  fluids  have  been  tried  and  recommended, 
of  which  one  is  sometimes  here,  another  sometimes  there  to  be 
used  with  success.  It  is  always  well  in  mounting  objects  not  to 
place  implicit  trust  in  such  recommendations,  but  rather  to 
make  a  series  of  experiments  with  various  preservative  fluids, 
of  which  only  the  best  are  to  be  retained  after  a  subsequent 
examination. 

M.  Schultze  has  recently  recommended,  as  a  medium  for 
mounting,  a  substance  used  by  botanists,  a  nearly  saturated 
solution  of  the  acetate  of  potash  in  water,  especially  for  osmic 
acid  preparations  which  do  not  bear  glycerine.  Without  re- 
moving the  covering  glass,  a  drop  of  this  strong  solution  of 
potash  is  added  to  the  microscopic  preparation  as  it  lies  in 
water  or  an  indifferent  solution.  A  day  later,  the  water  having 
been  in  the  mean  time  removed  by  evaporation,  the  cement  is  to 
be  applied  ;  although  one  may  wait  still  longer.  This  method 
has  been  used  for  more  than  two  years. 

Goadby's  solution,  the  conserving  liquor  of  the  English,  has 
obtained  a  certain  renown.  It  consists  of  : — 


213 

Bay  salt 4  ounces. 

Alum 2  ounces. 

Corrosive  sublimate 4  grains. 

Boiling  water 4  pints. 

This  composition,  which  brought  the  discoverer  a  consider- 
able sum,  does  not  prove  suitable  for  mounting  transparent 
preparations,  as  they  gradually  become  opaque  and  are  finally 
rendered  unserviceable.  On  the  contrary,  I  have  seen  opaque 
preparations  of  injections  mounted  in  this  fluid,  which  were 
made  in  England,  and  which  left  nothing  to  be  desired. 
Valentin  afterwards  remarked,  that  the  tissues  of  sea  animal- 
eulae  are  very  well  preserved  in  this  fluid.  The  beautiful  pre- 
parations of  vitreous-like  medusae,  salpidae,  etc.,  in  the 
naturalist's  collections  also  harmonize  with  this  observation. 

Pacini  has  recommended  certain  preservative  fluids,  as 
modifications  of  this  mixture,  which  contain  sublimate,  com- 
mon salt  or  acetic  acid,  but  no  alum,  including  glycerine,  how- 
ever, as  a  useful  addition,  and  intended  for  preserving  various 
tissues.  They  are  incomparably  more  serviceable  and  deserve 
accurate  consideration.  They  are  represented  by  the  following 
two  formulae : — 

'  Corrosive  sublimate 1  part. 

Pure  chloride  of  sodium 2  parts. 

Glycerine  (25°  Beaume) 13  parts. 

Distilled  water 113  parts. 

This  mixture  is  allowed  to  stand  for  at  least  two  months. 
After  that  time  it  is  prepared  for  use  by  mixing  one  part  of  it 
with  three  parts  of  distilled  water  and  filtering  it  through 
filtering-paper. 

Blood-corpuscles  are  preserved  in  it  exceedingly  well,  as  my 
own   observations  have  proved.     According  to   Pacini,   it  is 
equally  well  adapted  for  nerves  and  ganglia,  the  retina,  cancer 
cells,  and  especially  delicate  proteinous  tissues. 
A  second  mixture  consists  of : — • 

Corrosive  sublimate 1  part. 

Acetic  acid 2  parts. 

Glycerine  (25°  Beaume) 43  parts. 

Distilled  water 215  parts. 


214  SECTION   TETSTTH. 

This  mixture  is  prepared  for  use  in  the  same  manner  as  the 
preceding.  It  is  said  to  destroy  the  colored  blood-corpuscles, 
but  preserves  the  lymph-corpuscles  of  the  blood  intact. 

Further  modifications  of  these  mixtures,  as  they  are  employed 
in  the  Pathological  Institute  of  Berlin,  are  represented,  accord- 
ing to  Cornil,  by  the  following  : — 

1.  2. 

Corrosive  sublimate 1    Sublimate 1 

Chloride  of  sodium 2    Chloride  of  sodium 2 

Water 100   Water 200 

3.  4. 

Sublimate 1  Sublimate 1 

Chloride  of  sodium 2  Water 300 

Water 300 

5.  6. 

Sublimate 1  Sublimate 1 

Acetic  acid 1  Acetic  acid 3 

Water 300  Water 300 

7.  8. 

Sublimate 1  Sublimate 1 

Acetic  acid 5  Phosphoric  acid •. 1 

Water '. 300  Water 30 

No.  1  is  used  for  preserving  the  vascular  tissues  of  the  warm- 
blooded animals.  ISTo.  2  for  those  of  cold-blooded  creatures. 
No.  3  for  pus-corpuscles  and  related  structures.  No.  4  for 
blood-globules.  No.  5  is  intended  for  epithelial  cells,  connec- 
tive tissues,  and  pus-cells,  when  the  nuclei  are  to  appear 
at  the  same  time.  No.  6  is  applied  to  the  preservation 
of  connective-tissue  structures,  the  muscles  and  nerves.  No.  7 
serves  for  glands,  and  No.  8,  finally,  for  cartilaginous  tissues. 

Very  dilute  solutions  of  corrosive  sublimate  are  in  fact  very 
useful  as  preservative  fluids,  but  the  degree  of  concentration 
should  be  determined  every  time  they  are  used,  for  which  rea- 
son it  is  judicious  to  mount  several  examples  of  a  preparation 
in  solutions  of  different  strengths.  Harting  recommends  solu- 
tions of  1  part  of  corrosive  sublimate  to  200-500  of  distilled 
water.  He  remarks  that  it  is  onlv  in  such  solutions  that  he  is 


THE    MOUNTING,    ETC.  215 

able  to  preserve  the  blood  corpuscles.  Those  of  man  and  the 
mammalia  require  ^¥  of  the  sublimate,  those  of  birds  -5-^-,  those 
of  frogs  -f-^-Q.  Some  of  these  solutions  which  I  have  tested 
appear  to  be  useful.  His  recommendation  of  these  solutions 
for  the  brain,  spinal  cord,  and  retina  appears  less  justifiable, 
but,  on  the  contrary,  they  are  useful  for  cartilage,  muscle,  and 
crystalline  lens.  All  solutions  of  corrosive  sublimate  readily 
cause  the  preparations  to  become  dark  and  less  transparent. 

Chromic  Acid  and  Chromate  of  Potash. — Dilute  solutions 
of  chromic  acid  and  of  the  bichromate  of  potash,  combined 
according  to  circumstances  with  glycerine,  may  be  advanta- 
geously employed  as  preservative  fluids.  A  mixture  of  equal 
parts  of  glycerine  and  Miiller's  preservative  fluid  (p.  139)  appears 
to  be  very  useful.  The  latter,  undiluted,  also  occasionally  forms 
a  very  serviceable  medium  for  mounting  very  delicate  textures. 

A  solution  of  chloride  of  calcium  is  a  fluid  popular  with  the 
botanists  for  mounting.  It  appears  to  be  less  serviceable  for 
animal  specimens.  Ilarting  praises  the  saturated  solution  of 
the  pure  salt,  or  one  diluted  with  the  4-8  fold  volume  of  water. 
Preparations  of  teeth  and  bones  and  sections  of  hairs  are  said  to 
keep  well  in  it.  I  acknowledge  that  thus  far  my  experiments, 
not  very  numerous,  it  is  true,  with  the  solution  of  chloride  of 
calcium  have  afforded  me  only  very  moderate  results. 

Ilarting  recommends  solutions  of  the  carbonate  of  potash  in 
200-500  parts  of  water  as  the  best  medium  for  mounting  nerve 
fibres.  I  have  had  no  experience  with  this  solution.  Accord- 
ing to  the  same  authority,  arsenate  of  potash  in 'solution  with 
160  parts  of  water  also  exerts  the  same  effect  on  nerve  fibres. 

Watery  Solution  of  Creosote. — According  to  Ilarting's  ex- 
perience, a  solution  obtained  by  the  distillation  of  creosote  with 
water,  or  the  saturated  and  filtered  solution  of  creosote  in  a 
mixture  of  1  part  alcohol  of  32°  and  20  parts  of  water  is  a  good 
preservative  medium  for  many  tissues,  such  as  muscle,  connec- 
tive tissue,  tendon,  decalcified  bones  and  teeth,  and  likewise  the 
crystalline  lens. 

Arsenious  Acid. — This  is  to  be  boiled  with  water  in  excess, 
and,  after  cooling,  filtered  and  diluted  with  three  times  its  vol- 
ume of  water.  It  is  used  for  the  same  purposes  as  the  solution 


216  SECTION    TENTH. 

of  creosote,  and  is  also  suitable  for  the  preservation  of  fat  cells 
(Ilarting). 

Methyl  alcohol,  considerably  diluted  with  water,  in  the  pro- 
portion of  one  to  ten,  has  been  recommended  by  Quekett.  If, 
after  several  days,  the  fluid  becomes  cloudy,  it  should  be  fil- 
tered. Like  the  acetic  acid  solution,  it  causes  most  prepara- 
tions to  assume  a  granulated  condition  after  a  time. 

Methyl  alcohol  and  creosote  are  also  elements  of  a  compli- 
cated fluid  mentioned  by  Beale. 

Creosote 3  drachms. 

Wood  naphtha 6  ounces. 

Distilled  water 64       " 

Chalk,  as  much  as  may  be  necessary. 

It  is  prepared  in  the  following  manner  : — Mix  first  the  naph- 
tha and  creosote,  then  add  as  much  prepared  chalk  as  may  be 
sufficient  to  form  a  thick,  smooth  paste ;  afterwards  add,  very 
gradually,  a  small  quantity  of  the  water,  which  must  be  well 
mixed  with  the  other  ingredients  in  a  mortar.  Add  two  or 
three  small  lumps  of  camphor  and  allow  the  mixture  to  stand 
in  a  lightly  covered  vessel  for  a  fortnight  or  three  weeks,  with 
occasional  stirring.  The  almost  clear  supernatant  fluid  may 
then  be  poured  off  and  filtered  if  necessary.  It  should  be  kept 
in  well-corked  or  stoppered  bottles.  This  mixture  forms  a 
modification  of  Thwaite's  fluid  for  preserving  desmidiae. 

Topping* s  Fluids. — He  recommends  the  employment  of  one 
part  of  absolute  alcohol  to  five  parts  of  water ;  and  where  the 
preservation  of  delicate  colors  is  necessary,  he  dissolves  one  part 
of  acetate  of  alumina  in  four  parts  of  distilled  water.  The 
latter  mixture,  diluted  with  an  equal  volume  of  glycerine,  has 
preserved  carmine  injections  for  me  very  well  over  three  years. 
Deands  Fluid. — He  praises  a  mixture  of  six  ounces  of  pure 
glycerine,  nine  ounces  of  honey,  a  little  alcohol,  and  a  few  drops 
of  creosote,  for  the  preservation  of  animal  and  vegetable  struc- 
tures. The  mixture  is  to  be  filtered  while  warm. 

Plain  slides  and  covering  glasses  may  be  used  for  mounting 
very  thin  objects.  A  larger  or  smaller  drop,  as  may  be  neces- 
sary, of  the  preserving  fluid  may  be  placed  immediately  on  to 
the  former  by  means  of  a  brush  or  a  glass  rod,  and  the  specimen, 


217 

seized  with  delicate  forceps  or  a  cataract  needle,  is  placed  in 
this,  care  being  taken  that  it  is  covered  by  the  fluid.  The  cov- 
ering glass,  the  under  surface  of  which  has  been  breathed  on,  is 
then  placed  over  the  specimen  in  the  manner  indicated  for 
mounting  in  Canada  balsam.  One  should  avoid  employing  too 
large  a  quantity  of  the  preservative  fluid,  as  it  is  then  liable  to 
escape  at  the  sides,  or  to  flow  over  the  edges  of  the  covering 
glass.  In  such  cases  the  excess  should  be  removed  by  means  of 
a  very  finely  pointed  pipette,  or  by  the  application  of  narrow 
strips  of  bibulous  paper.  In  both  cases  the  edges  are  also  to 
be  dried  with  a  linen  rag,  care  being  at  the  same  time  taken  not 
to  displace  the  cover.  Sometimes  air-bubbles  remain  and  can 
only  be  removed  by  slight  pressure.  It  is  well  to  cut  a  piece 
of  fine  writing-paper  about  an  inch  long  in  such  a  manner  as 
that  it  will  form  a  long,  narrow  triangle,  measuring  about  2X// 
at  its  base.  The  point  of  this  is  now  to  be  passed  between  the 
slide  and  covering  glass ;  frequently  the  air-bubble  can  be 
conveniently  shoved  out  with  it. 

Although  with  Canada  balsam  as  soon  as  the  covering  glass  is 
successfully  placed  in  position  the  whole  process  is  essentially 
terminated,  a  further  enclosure  of  the  edges  not  being  in  reality 
necessary,  although  even  here  the  specimen  receives  greater 
protection  and  a  more  attractive  appearance  by  means  of  a 
finishing  touch;  it  is  otherwise  with  objects  mounted  moist; 
they  must  be  cemented  ; — a  procedure  which  will  receive  more 
especial  mention  further  below. 

If,  however — and  this  will  generally  be  the  case — a  somewhat 
thicker  object  is  to  be  mounted,  or  if  it  be  feared  that  the 
cement  as  it  hardens  will  subsequently  press  the  covering  glass 
too  much  against  the  preparation  and  thus  injure  it,  a  firm  sub- 
stance should  be  interposed  between  the  two  glasses.  Silver 
wires  or  narrow  strips  of  paper  are  to  be  recommended  as  sim- 
ple contrivances ;  various  thicknesses  of  them  may  be  prepared 
and  placed  under  two  opposite  borders  of  the  covering  glass,  or 
a  narrow  paper  frame  may  be  substituted.  But  then  the  in- 
sinuation of  an  air-bubble  is  quite  possible,  and  the  first  layer 
of  cement  should  not  consist  of  a  substance  which  is  very  fluid 
or  whicli  hardens  very  slowly,  as  it  would  then  either  penetrate 


218  SECTION   TENTH. 

into  the  preserving  fluid  immediately,  or  the  external  coating 
would  afterwards  in  contracting  press  in  the  internal  layers. 

This  procedure,  in  its  further  development,  leads-  to  the  con 
struction  of  a  framework  which  is  sometimes  shallow,  sometimes 
deep,  and  which  is  fastened  to  the  slide.     The  flat  case  thus  ob- 
tained is  called  a  cell. 

Very  manifold  directions  have  been  given  concerning  the  con- 
struction of  such  cells.  The  more  simple  ones  will  be  preferred 
unless  greater  cheapness  renders  another  procedure  desirable. 

Cells  may  be  made  of  gutta-percha,  caoutchouc,  and  glass. 
The  latter  are  the  best,  but  also  the  most  expensive. 

Gutta-percha  Cells. — Gutta-percha  occurs  in  commerce  in 
sheets  of  varying  thickness.  A  good  sheet  should  be  even, 
homogeneous,  and  flexible.  If  crooked  or  cracked,  it  may  be 
made  to  assume  the  former  condition  by  dipping  it  in  boiling 
water.  With  a  ruler  and  knife  quadratic  or  oblong  square 
pieces  may  be  cut  out  in  the  same  \vay  as  from  pasteboard ; 
they  should,  however,  be  narrower  than  the  slide.  In  these  a 


Fig.  81.     Gutta-percha  cell. 

round,  oval,  or  oblate  square  aperture  is  to  be  cut  with  a  punch 
and  hammer,  to  contain  the  preparation  and  the  conserving  me- 
dium (fig.  81). 

CaoutohouG  Cells. — These  are  also  made  from  the  commercial 
sheets,  which  may  be  placed  one  over  the  other  and  readily 
made  to  stick  together  by  heating  them,  when  it  is  necessary 
to  construct  cells  with  high  walls. 

Glass  Cells. — These  deserve  the  preference,  but  if  bought 
ready  made  from  the  glass-cutter  they  are  rather  more  expen- 
sive. Glass  rings  of  different  diameters  and  varying  depths 
are  used,  but  they  have  the  inconvenience  of  requiring 
circular  covering  glasses.  Quadratic  or  oblong  square  plates, 


TILE,    MOUNTING,    ETC. 


219 


resembling  those  of  gutta-percha,  and  provided  with  circular 
openings,  are  useful.  Those  of  half  a  line  in  depth  and  with 
a  round  aperture  of  about  four  lines  in  diameter  will  be  found 
to  suffice  for  most  histological  purposes. 

Excellent  glass  cells,  made  in  England,  have  lately  been 
brought  to  my  knowledge  through  Thiersch.  They  are  made 
of  glass  slides  several  lines  in  thickness,  perforated  by  a  circular 
aperture  of  considerable  size,  with  covering  glasses  cemented 
to  both  surfaces.  The  perfectly  injected  eyes  of  white  rabbits, 
divided  in  halves  and  thus  mounted  with  their  natural  curva- 
ture in  Canada  balsam,  constitute  one  of  the  handsomest  pre- 
parations which  Thiersch  has  produced. 


Fig.  82.     Glass  cell  with  cover. 

Any  one  to  whom  economy  of  time  is  of  less  inportance,  can 
himself  prepare  glass  cells  in  still  another  way  (fig.  82).  He 
should  have  strips  a  line  or  so  in  breadth,  cut  from  plate-glass 
(or,  if  able  to  use  the  diamond,  he  may  cut  them  himself) ;  these 
should  be  of  two  sorts,  one  of  6-7 '"  in  length,  another  form 
only  3-4 '"  in  length.  With  these  the  walls  of  the  cell  are  to 
be  constructed. 

Beale,  who,  as  is  customary  with  Englishmen,  explains  the 
matter  accurately,  gives  several  additional  practical  directions. 

A  thin  glass  cover  may  be  used  for  the  construction  of  very 
shallow  cells.  The  thin  glass  may  be  cemented  while  warm 
to  a  glass  ring,  or  over  a  hole  in  a  plaro  of  glass,  by  means  of 
the  marine  glue  which  is  soon  to  be  described.  A  hole  is  then 
to  be  forced  through  it  with  the  point  of  a  throe-cornered  file, 
and  this  is  to  be  enlarged  to  the  margin ;  the  cracks  do  not 
extend  across  that  part  of  the  glass  which  is  cemented.  The 
perforated  glass  may  be  readily  removed  when  again  heated. 

A  blunt-cornered,  square  cell  may  be  made  by  bending  a  sin- 


220  SECTION    TENTH. 

gle  strip  of  glass  in  the  blow-pipe  flame  and  melting  the  ends 
together.  Beale  recommends  flint-glass  for  this  purpose.  In 
practised  hands,  this  is  certainly  a  very  good  way  of  making 
deep  and  large  cells. 

All  these  cells  must  be  cemented  to  the  slide.  But  gutta- 
percha  may  be  warmed  in  hot  water,  and  its  under  surface  then 
carefully  dried  and  secured  to  the  heated  slide.  This  method 
has  not  proved  to  be  durable. 

Marine  glue  may  be  used,  after  the  manner  of  the  English, 
for  cementing  the  glass  cells. 

This  substance  is  prepared  by  dissolving,  separately,  equal 
parts  of  shellac  and  india-rubber  in  naphtha,  and  afterwards 
mixing  the  solutions  thoroughly,  with  the  application  of  heat. 
It  may  be  rendered  thinner  by  the  addition  of  more  naphtha. 
Marine  glue  is  also  readily  dissolved  by  ether  or  a  solution  of 
potash.  According  to  Quekett,  the  variety  known  in  commerce 
as  G.  K.  4  is  best  adapted  for  microscopic  purposes. 

The  following  process  is  necessary  for  cementing  with  marine 
glue  :  The  slide  is  to  be  warmed  on  a  heated  plate  of  metal  (the 
English  use  a  table  of  sheet-iron  supported  by  four  feet,  with  a 
spirit-lamp  burning  under  it).  A  narrow  strip  of  the  cement  is 
then  melted  on  the  heated  slide  and  made  to  extend  over  all  the 
places  on  which  the  walls  of  the  cell  are  to  rest.  Firm  pressure 
is  then  to  be  made  over  the  cell,  and  the  whole  placed  aside  to 
cool.  The  excess  of  glue  may  afterwards  be  removed  with  the 
blade  of  a  knife.  A  weak  solution  of  potash  may  be  used  for 
cleaning  the  cell. 

According  to  Ilarting,  the  following  mixture  serves  for  ce- 
menting the  india-rubber  cell :  One  part  of  very  finely  divided 
gutta-percha  is  to  be  mixed  with  fifteen  parts  of  oil  of  turpen- 
tine, and  dissolved  at  a  gentle  heat  with  constant  stirring.  It 
is  then  to  be  filtered  through  cloth,  and  one  part  of  shellac 
added  to  the  filtrate  ;  this  is  also  to  be  dissolved  at  a  moderate 
temperature  and  with  constant  stirring.  The  heating  is  to  be 
continued  until  a  drop  of  the  mixture,  when  allowed  to  fall  on 
a  cool  surface,  becomes  tolerably  hard.  In  this  condition,  the 
cement  is  ready  for  use.  "When  afterwards  used,  a  little  oil  of 
turpentine  is  to  be  added. 


THE    MOUNTING,    ETC.  221 

In  order  to  fasten  a  caoutchouc  cell,  it  is  first  to  be  held 
under  the  centre  of  the  slide ;  and  exactly  over  it,  on  the  upper 
surface  of  the  slide,  a  thin  layer  of  the  warm  cement  is  to  be 
laid  on  with  a  brush.  The  cell  is  now  to  be  pressed  into  posi- 
tion on  the  upper  surface  of  the  heated  slide,  which  is  then 
turned  over  and  allowed  to  lie  on  a  flat  surface  till  the  cement 
has  cooled. 

Harting's  gutta-percha  cement  may  also  bo  used  in  the  same 
manner  for  fastening  glass  cells,  and  for  building  them  out  of 
four  strips  of  glass. 

The  latter  may  also  be  accomplished  with  still  another  cement. 

1  part  of  india-rubber  is  to  be  dissolved  in  64  parts  of  chlo- 
roform, and  then  16  parts  of  dried  powdered  mastic  added. 
A  thin  layer  of  the  cold  mixture  is  to  be  placed  on  the  slide 
with  a  brush ;  the  cell  is  then  to  be  warmed  and  pressed  into 
position. 

Whichever  method  is  employed,  it  is  well  to  fasten  the  cell 
as  carefully  as  possible,  in  order  that  no  leak  or  entrance  of  air 
into  the  cell  may  afterwards  occur.  A  glass  cell  should  always 
have  a  roughened  surface  for  the  cement.  The  surfaces  may 
readily  be  roughened  by  rubbing  on  a  flat  stone  with  emery 
powder. 

Cells  of  tin-foil  have  also  been,  recommended,  but  I  have  had 
no  personal  experience  with  them. 


Fig.  83.  Placing  the  covering-glass  in  position. 

Cells  may  also  be  made  with  certain  cements ;  these  are  en- 
tirely sufficient  for  many  thin  objects.  Asphalt  may  be  used 
for  this  purpose,  although  1  do  not  esteem  it  very  highly.  A 
white  cement,  made  by  the  artist  Ziegler,  in  Frankfort-on-the- 
Main  (Friedberger  Gasse  23),  is  better,  and  serves  very  well  for 
this  purpose.  An  oblong  square,  a  quadrate,  or  a  circle  may 
be  made  with  it  on  a  slide,  and  left  to  harden. 


SECTION   TENTH. 

The  cell  having  been  filled  with  the  preservative  fluid,  and 
the  object  immersed  in  it,  and  care  having  been  taken  that 
there  are  no  air  bubbles  present,  the  covering-glass  is  breathed 
on  and  placed  in  position  in  the  usual  manner  (fig.  83).  The 
latter  should  always  be  somewhat  smaller  than  the  cell,  so  as 
not  to  completely  cover  its  outer  margin.  The  superfluous 
fluid  is  to  be  removed  with  caution,  however,  as  otherwise  air- 
bubbles  may  again  enter. 

Now  commences  the  cementing  of  the  covering-glass.  This 
must  be  done  at  once,  unless  the  preservative  fluids  be  glycerine 
or  a  solution  of  chloride  of  calcium,  in  which  case  the  process 
may  be  delayed. 

A  considerable  number  of  cements  have  come  into  use,  and 
preparations  may  be  mounted  with  several  of  them  with  equal 
perfection  and  security. 

At  present  a  solution  of  asphalt  (Brunswick  black)  is  most 
frequently  used.  Various  sorts  occur  in  commerce ;  it  consists 
of  a  solution  of  asphalt  in  linseed  oil  and  turpentine. 

Good  Brunswick  black  should  have  a  transparent,  homo- 
geneous black  appearance.  As  in  the  application  of  other 

cements,  a  camel's-hair  brush 
is  used,  the  stroke  passing 
along  the  edge  of  the  cover, 
whereby  the  latter  as  well  as 
the  slide  receives  a  stripe  of 
cement  (fig.  84).  With  a  little 
practice,  one  soon  learns  to 
judge  of  the  proper  quantity 
to  use,  and  to  draw  a  hand- 
Fig.  84.  Making  a  border  with  Brunswick  black.  SOme  Border.  If,  111  the 

course  pf  time,  the  Bruns- 
wick black  becomes  too  thick,  it  may  be  diluted  with  turpen- 
tine. Besides  being  dirty  to  handle,  it  also  has  the  disadvantage 
of  having  a  tendency  to  become  cracked  and  fissured,  and,  after 
weeks  and  months,  in  consequence  of  its  further  contraction,  to 
press  the  fluid  out  from  the  cell.  It  has  therefore  been  recom- 
mended to  strengthen  the  margins  about  every  six  months  with 
a  new  layer  of  cement.  This  cement  may  also  be  considerably 


ETC.  223 

improved  by  the  addition  of  a  small  quantity  of  a  solution  of 
caoutchouc  in  benzine. 

In  consequence  of  its  great  tendency  to  the  above-mentioned 
defects,  I  have,  of  late,  either  entirely  ceased  to  use  the  ordinary 
Brunswick  black,  or  only  use  it  for  the  first  coating,  especially 
when  strips  of  paper  are  placed  between  the  slide  and  cover, 
and  then,  after  several  days,  an  external  layer  of  cement  is  to  be 
placed  over  this. 

I  have  recently  become  acquainted  with  the  Brunswick  black 
used  'by  Bourgogne,  of  Paris,  and  can  only  speak  of  it  in  the 
highest  terms.  Unfortunately,  its  composition  is  unknown  to 
me.  It  dries  with  comparative  rapidity  and  a  single  coating  is 
quite  sufficient. 

[A  very  good  and  durable  substitute  for  Brunswick  black  may 
be  found  in  the  "  Liquid  Stove  Polish,"  prepared  in  England 
and  sold  in  this  country.] 

A  fluid  mixture,  coming  from  England  under  the  name  of 
gold-size,  is  excellent  for  cementing  preparations  of  thin  objects 
mounted  in  glycerine,  and  is  also  to  be  recommended  as  being 
clean  to  handle.  It  is  a  complicated  mixture.  Beale  gives  the 
following  directions  for  its  composition : — 25  parts  of  linseed 
oil  are  to  be  boiled  with  one  part  of  red  lead,  and  a  third  part 
as  much  umber,  for  three  hours.  The  clear  fluid  is  to  be  poured 
off  and  mixed  writh  equal  parts  of  white  lead  and  yellow  ochre, 
which  have  been  previously  well  pounded.  This  is  to  be  added 
in  small  successive  portions,  and  well  mixed ;  the  whole  is  then 
again  to  be  well  boiled,  and  the  clear  fluid  poured  off  and  kept 
in  a  bottle  for  use. 

It  is  applied  with  a  brush  ;  a  second  layer  may  be  added  after 
half  a  day.  It  is  better  to  leave  specimens  thus  prepared  for  a 
considerable  time  before  making  the  final  application  of  cement. 

I  use  Ziegler's  white  cement  as  a  final  coating;  it  may  also  be 
used  alone  with  the  most  perfect  security.  It  has  been  recently 
improved  by  Ilerr  Meyer,  the  proprietor  of  the  Hirsch  Apothe- 
cary, in  Frankfort.  It  is  a  somewhat  thick  mass  and  may  be 
diluted  at  pleasure  with  oil  of  turpentine,  at  a  moderate  tem- 
perature. A  thin  layer  applied  with  a  brush  suffices  for  glyce- 
rine preparations.  A  somewhat  thicker  layer,  surrounding  the 


224  SECTION   TENTH. 

cover  like  a  wall,  is  generally  applied,  and  is  very  useful  as  a 
protection  to  the  latter,  and  in  no  wise  detracts  from  the  good 
appearance  of  the  preparation. 

This  white  cement  generally  dries  very  slowly,  so  that  an 
impression  may  be  made  in  it  even  after  a  long  time.  One 
should  therefore  be  careful  not  to  lay  such  preparations  on 
each  other,  and  especially  to  avoid  all  opportunities  for  any- 
thing to  stick  to  them.  But  when  once  hardened  there  is  no 
danger  of  the  occurrence  of  cracks  or  flaws,  and  scarcely  any 
of  a  leakage.  Irregularities  of  the  external  margin  may  be 
remedied  after  a  few  days  with  the  blade  of  a  knife ;  but  por- 
tions of  the  cement  which  have  run  over  the  surface  of  the 
cover  should  be  left  untouched  for  months.  Oil  of  turpentine 
or  benzine  may  be  used  to  clean  the  brushes  or  glass. 

As  the  composition  of  Ziegler's  cement  remains  unknown, 
we  have  to  thank  Stieda  for  a  communication  giving  the  direc- 
tions for  composing  a  similar  cement.  Oxide  of  zinc  is  to  be 
rubbed  up  with  a  corresponding  quantity  of  oil  of  turpentine, 
and  while  rubbing,  for  each  drachm  of  the  oxide  of  zinc  an 
ounce  of  a  solution  of  the  consistence  of  syrup  of  gum  damar 
in  oil  of  turpentine  is  to  be  added.  If  another  color  than  white 
be  desired,  cinnabar  may  be  used  in  the  place  of  the  oxide  of 
zinc,  using  two  drachms  to  the  ounce. 

Schacht  recommended  the  so-called  mask  lac,  which  dries 
very  rapidly,  as  a  cement  for  wet  preparations,  and  also  as  a 
coating  for  specimens  mounted  in  Canada  balsam  or  copal. 
The  variety  of  lac  used  by  him  is  designated  as  No.  3,  at  Bese- 
ler's  lac  manufactory  in  Berlin  (Schutzen  Strasse,  No.  66).  I 
made  considerable  use  of  this  lac  several  years  ago,  and  do  not 
hesitate  to  recommend  it  as  being  the  next  best  to  Bourgogne's 
cement. 

We  also  mention  a  cement  which  is  to  be  used  in  the  manner 
already  indicated  as  a  final  coating  for  Canada  balsam  prepara- 
tions. We  are  indebted  for  a  knowledge  of  this  to  a  friendly 
communication  from  Thiersch. 

When  the  specimens  have  been  mounted  for  several  days, 
weeks,  or  even  months  in  pure  Canada  balsam,  or  a  solution  of 
the  same  in  chloroform,  they  are  surrounded  with  a  border  of 


THE    MOUNTING,    ETC.  225 

Canada  balsam  dissolved  in  chloroform,  in  the  manner  indicated 
above  (fig.  84)  for  asphalt.  Later — but  never  before  the  second 
or  third  day,  still  better  after  weeks  or  months — a  final  coating 
is  to  be  applied.  This  consists  of  a  colored  and  thick  varnish 
of  shellac.  It  is  found  ready  prepared  with  alcohol  at  the 
wholesale  druggists.  It  is  to  be  carefully  evaporated  to  the  con- 
sistence of  thin  mucilage  and  colored  with  a  filtered,  concen- 
trated solution  of  anilin  blue  or  gamboge  in  absolute  alco- 
hol. Finally,  about  a  scruple  of  castor-oil  is  to  be  added  to 
each  ounce  of  the  mixture,  and  after  some  further  evaporation 
it  is  to  be  preserved  in  a  well-closed  vessel.  If,  after  a  time,  it 
should  become  too  concentrated,  this  may  be  remedied  by  the 
addition  of  a  few  drops  of  absolute  alcohol. 

This  varnish  is  to  be  applied  with  a  brush  to  the  borders  of 
the  Canada  balsam.  It  becomes  hard  in  a  few  hours,  and  then 
forms  an  elegant  and  hermetic  covering  for  objects  mounted  in 
resinous  substances. 

This  blue  shellac  varnish  also  forms  a  good  finishing  coat  for 
objects  which  have  been  mounted  wet  and  cemented  with  gold- 
size. 

Finally,  the  form  and  size  of  the  slides  are  not  unimportant 
for  the  elegant  appearance  of  a  collection  of  preparations. 
Similarity  of  form,  so  far  as  it  is  possible,  is  desirable  for 
greater  convenience  of  keeping  or  of  occasional  transportation. 

The  art  of  grinding  the  edges  of  the  slides  may  soon  be 
learned  by  employing  a  very  thick  plate  of  glass  and  a  fine  sort 
of  emery  powder,  which  is  to  be  made  into  a  paste  with  water. 

The  slide  should  not  be  too  small,  so  that  sufficient  space  may 
be  left  at  the  ends  of  the  preparation  to  affix  two  labels,  one  of 
which  is  to  contain  the  general  designation,  while  on  the  other 
especial  remarks,  the  number  of  the  collection,  etc.,  may  be 
placed.  In  certain  cases  there  should  also  be  room  left  for  the 
indicator.*  Such  slides  will  frequently  afford  room  for  lar- 

*  Various  indicators  or  object-finders  have  been  proposed  for  enabling-  one  to 
find  any  particular  place  in  a  preparation.  Fine  divisions,  like  those  of  a  rule, 
may  be  photographed  on  narrow  strips  of  paper,  and  one  of  these  strips  pasted 
at  one  of  the  broad,  and  one  at  one  of  the  narrow  margins  of  the  cover ;  for 
example,  at  the  right  and  the  lower  side  of  fig.  85.  A  rectangular  plate  of 
15 


226 


SECTION   TENTH. 


ger  objects  and  thus  render  it  unnecessary  to  select  a  different 
form  for  special  objects ;  as,  for  example,  when  an  extensive 
section  of  bone  or  a  voluminous  injected  preparation  is  to  be 
mounted. 

I  prefer  a  glass  slide  like  those  of  the  English  collections, 
three  British  inches  long  by  one  inch  wide  (72  mm.  by  24  mm.), 
above  all  others  (fig.  85).  The  preparations  of  Bourgogne  of 


Pig.  85.  English  object  slide. 

Paris  also  have  this  convenient  and  handsome  form.  Slides  of 
a  larger  size  are  unnecessary  and  appear  too  unwieldy.  But 
those  of  a  smaller  size  should  also  never  be  employed.  A  pattern, 
proposed  in  Giessen,  48  mm.  in  length  by  28  mm.  in  width,  is 
inelegant,  and  much  less  convenient  than  the  English. 

If  it  be  desired  to  place  microscopic  preparations  in  layers, 
for  the  sake  of  greater  economy  of  room,  either  in  keeping  or 
in  transporting  them,  the  employment  of  protection-ledges 
(Schutzleisten)  is  to  be  recommended.  These  are  narrow  strips 
of  glass  which  are  to  be  cemented  across  the  slide  at  either  side 
«f  the  object.  They  should  naturally  be  higher  than  the  cover 
and  the  cell.  Although  this  arrangement  is,  of  itself,  quite 

metal,  or,  better  still,  a  small  square,  consisting  of  two  narrow  strips  of  brass 
meeting  each  other  under  an  angle  of  90",  is  used  for  ascertaining  the  particular 
portion  of  the  object ;  this  is  to  be  noted  on  the  preparation,  and  may  be  again 
readily  found  with  the  little  plate  or  the  square.  The  best— because  the  most 
simple — arrangement  has  been  indicated  by  Hoffmann.  Two  crosses  are  to  be 
scratched  at  either  side  of  the  aperture  of  the  object  stage  of  the  microscope, 
the  one  standing  (  +  ),  the  other  reclining  (  x  ).  If,  now,  the  portion  of  the 
preparation  to  be  marked  is  situated  in  the  centre  of  the  field,  both  crosses  are 
to  be  drawn  with  ink  on  the  slide  exactly  over  those  of  the  stage.  It  is  Only 
necessary  to  place  these  marks  over  each  other  again  in  order  to  at  once  find 
the  object. 


THE    MOUNTING,    ETC.  227 

practical,  it  nevertheless  diminishes  the  room  necessary  for  the 
labels  to  an  unpleasant  extent. 

For  preserving  and  arranging  specimens,  boxes  of  wood  or 
pasteboard,  with  grooved  wooden  racks  at  the  sides,  which  hold 
the  slides  securely,  are  occasionally  used.  As,  with  these,  the 
slides  stand  vertically  and  the  preparations  may  in  consequence 
readily  sink,  when  mounted  in  resinous  substances  which  have 
not  thoroughly  hardened,  or  when  other  fluid  media  have  been 
used,  the  upright  position  of  such  boxes  deserves  the  preference. 
On  the  other  hand,  trays  of  wood  or  pasteboard  with  very  low 
borders,  or  plain  drawers  may  be  used  ;  they  may  either  be  ar- 
ranged to  slide  out,  like  a  chest  of  drawers,  or  they  may  simply 
rest  on  each  other  and  be  removed  from  the  chest  by  means  of 
loops.  Slides  of  the  most  varying  sizes  may  be  conveniently 
placed  in  them  at  the  same  time,  and  the  sinking  of  the  prepa- 
ration is  also  avoided.  This  arrangement,  however,  is  not  ser- 
viceable for  transportation. 

Here,  as  with  all  collections  (increasing  in  degree  with  its 
growth),  regularity  and  occasional  revision  are  imperatively 
necessary. 

As  every  assiduous  microscopist  of  the  present  time  possesses 
his  own  collection  of  preparations,  so  likewise  do  the  various 
microscopical  associations  of  Germany.  For  example,  those 
of  Frankfort-on-the-Main  and  of  Giessen,  as  also  the  Micro- 
scopical Society  of  London. 

Among  the  private  collections  we  enumerate  the  celebrated 
one  (preparations  of  injections)  of  Ilyrtl,  in  Vienna ;  that  of 
Kolliker,  in  Wiirzburg  ;  Gerlach,  in  Erlangen ;  those  of  Thiersch 
and  Leuckart,  in  Leipzig  ;  Welcker,  in  Halle  ;  and  Schultze,  in 
Bonn.  In  Holland  is  the  collection  of  Harting  ;  in  London  are 
those  of  Carpenter,  L.  Beale,  L.  Clarke,  and  others,  likewise  that 
of  the  College  of  Surgeons ;  in  Manchester,  that  of  Williamson. 
Among  the  Swiss  collections  may  be  mentioned  those  of  His, 
in  Basel ;  in  Zurich,  those  of  Goll  and  myself. 

Preparations  may  be  purchased  of  Ilyrtl  and  G.  A.  Lenoir, 
in  Vienna ;  J.  D.  Moller,  in  AVedel,  IIoLstein ;  C.  Rodig,  in 
Hamburg ;  Schaffer  and  Budenberg,  in  Magdeburg  ;  Bom-gogno 
(9  Rue  de  Rennes),  Paris ;  of  Smith  and  Beck,  also  of  Topping 


228  SECTION   TENTH. 

(4  New  "Winchester  Street,  Pentonville),  and  of  Pillischer  (88 
New  Bond  Street),  London.  Injections  and  other  preparations 
of  the  author  are  to  be  obtained  from  the  Magdeburg  establish- 
ment already  mentioned,  from  Lenoir,  in  Vienna,  and  from  the 
optician  Th.  Ernst,  in  Zurich. 

[The  histological  and  pathological  preparations  of  Dr.  Edward 
Curtis,  which  are  models  of  elegance  and  neatness,  may  be  pur- 
chased of  Queen,  who  also  has  for  sale  those  of  Dr.  J.  W.  S. 
Arnold. 

Dr.  Francis  Delafield  also  has  a  very  large  assortment  of 
pathological  and  histological  preparations  at  the  "  Pathological 
Laboratory  of  Bellevue  Hospital."] 


Section 


BLOOD,  LYMPH,  CHYLE,  MUCUS,  AND  PUS. 

THE  investigation  of  these  cell-containing  fluids  belongs  to 
the  more  easy  and  simple  labors  of  the  microscopist,  inasmuch 
as  a  drop  of  the  same,  having  been  placed  on  the  slide  by  means 
of  a  glass  rod,  and  spread  out  into  a  thin  layer  by  the  covering 
glass,  suffices  for  the  first  examination.  But  care  is  to  be  used 
in  the  selection  of  actually  indifferent  media,  especially  in  the 
examination  of  living  cells. 

1.  Among  the  animal  fluids  mentioned  the  blood  is  the  most 
delicate  substance,  so  that  circumspection  is  necessary  for  the 
recognition  of  its  normal  condition. 

In  order  to  examine  human  blood,  it  is  only  necessary  to 
prick  the  point  of  the  finger  and  allow  a  drop  to  exude,  which 
is  then  received  on  the  slide.  For  more  continued  and  prolonged 
investigations  a  quantity  of  blood  is  to  be  obtained  by  means  of 
venesection,  and  beaten  to  separate  the  fibrin.  The  blood  of 
the  smaller  animals  is  to  be  obtained  by  opening  one  of  the 
larger  vessels  or  the  heart ;  the  blood  may  be  received  in  a  test 
tube.  If  allowed  to  remain  in  this,  or  in  a  cylindrical  vessel, 
the  cells  gradually  sink  and  the  serum  which  remains  above 
them  becomes  colorless.  This  fluid  is  the 
best  medium  for  use  in  the  investigation. 

In  consequence   of  the   extraordinarily 

large  number  in  winch  the  colored  cells  (fig.          *"Q  jj  "  ^g^...-^ 
86,  a,  b,  c)  occur  in  the  blood,  it  should  be 
spread  out  in  a  very  thin  layer,  so  as  to 
bring:  these  elements  distinctly  into  view.        ceiiT  a  a  seen  from 

J  above ;  &  half,  c  c  entire- 

Slight  compression  made  on  the  covering        wmfTJothtL?edei  d  & 
glass  with  the  point   of  the   needle   will 
facilitate  the  examination  considerably.     In  human  blood  (fig. 


230  SECTION"    ELEVENTH. 

86)  when  these  cells  have  their  broad  surface  turned  towards 
the  observer,  they  present  the  well-known  form  of  circular 
disks  (a  a),  but  when  standing  on  their  sides  they  appear  biscuit- 
shaped  (c  c). 

Dilution  of  the  blood  requires  some  little  attention.  The 
Berum  of  the  blood,  if  disposable,  is  best  for  this  purpose. 
Solutions  of  salt,  sugar,  or  crystalloid  matter  may  also  be  used 
with  advantage  for  a  momentary  examination,  provided  they 
are  of  the  proper  degree  of  concentration.  The  Pacinian 
fluid  (sublimate,  salt,  and  glycerine  with  water),  which  has 
already  been  mentioned  (p.  213),  is  very  suitable  if  it  happens 
to  be  at  hand,  and  I  know  of  no  other  fluid  which  is  capable 
of  preserving  our  cells  in  so  excellent  a  manner  for  years. 
The  iodine  serum  is  also  very  useful,  and  likewise,  according 
to  Rollett,  a  mixture  resembling  Muller's  eye  fluid.  The  latter 
consists  of  one  part  of  a  cold  saturated  solution  of  the  bichro- 
mate of  potash,  5  parts  of  a  similar  solution  of  the  sulphate 
of  soda,  and  10  parts  of  water. 

Such  dilutions  will  also  be  necessary  when  it  is  desired  to  cause 
the  colored  blood-cells  to  roll,  in  order  to  recognize  their  form. 
The  pressure  of  the  point  of  a  needle  on  the  edge  of  the  cover- 
ing glass  will  then  induce  the  desired  current  in  the  fluid. 

Upon  carefully  focussing,  the 
human  colored  blood  cells  will 
appear  to  present  a  yellowish  cir- 
cumference and  a  colorless  centre. 
If  the  tube  of  the  microscope 
be  depressed  a  little,  the  central 
portion  becomes  somewhat  darker. 
The  colorless  cells  of  the  blood 
originate  in  the  lymphatic  glands, 
the  spleen,  and  the  marrow  of 

Fig.  87.  Contractil^ceUs  from  human       ^^       Dillltion      wjth      ftn     indif_ 

fereiit  fluid  is  also  necessary  for 

their  recognition,  and,  in  consequence  of  the  small  number  of 
these  elements,  they  require  some  little  search  (fig.  87). 

Even  in  human  blood  taken  directly  from  the  vein,  one 
may  with  a  4-600  fold  enlargement,  and  without  any  further 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  231 

precautionary  measures,  observe  the  remarkable  changes  of 
form  of  the  living  colorless  cells,  which  may  slowly  pass 
through  the  series  of  alterations  which  we  have  sketched  (fig. 
87).  But  if  the  warm  stage  (p.  105)  and  a  temperature  of  38- 
40°  C.  be  used,  and  iodine  serum  added,  the  play  of  movements 
mentioned  becomes  extraordinarily  lively.  A  portion  of  the 
colorless  cells  now  creep  about  between  the  colored  blood- 
corpuscles  and  present,  with  constantly  changing  form,  the 
strangest  variety  of  shapes.  Granules  of  carmine,  molecules 
of  cinnabar  and  indigo,  which  have  been  added  to  the  fluid,  are 
now  readily  taken  up  into  the  cell-body  (Schultze).  An  ex- 
tremely fine  granulated  anilin  blue,  which  has  been  precipitated 
from  the  alcoholic  solution  by  means  of  water,  is  very  excellent. 
—If  this  apparatus  is  wanting,  one  may  readily  perceive  the 
same  condition  in  the  lymph  corpuscles  of  frog's  blood,  with 
the  aid  of  the  moist  chamber.  Very  beautiful  appearances  may 
be  obtained  with  the  latter  animal,  if  a  drop  of  its  fresh  blood 
be  allowed  to  coagulate  on  the  under  surface  of  the  covering 
glass,  in  a  moist  chamber  (after  the  manner  of  our  fig.  64). 
One  soon  notices,  after  a  zone  of  serum  has  formed  at  the  bor- 
ders of  the  coagulum,  that,  in  consequence  of  their  lively  wan- 
dering from  the  clot,  many  of  these  amoeboid  cells  have 
penetrated  the  ring  of  fluid,  and  that  the  surface  of  the  coagu- 
lum is  also  thickly  covered  by  them  (Hollett). 

We  will  here  mention  still  another  method  which  has  recent- 
ly led  to  scientific  results  of  the  highest  interest  (Colmheim). 

A  small  quantity  (at  most,  a  few  ccm.)  of  one  of  the  above- 
mentioned  finely  granulated  coloring  materials,  suspended  in 
water,  is  to  be  injected,  for  several  days  after  each  other, 
into  one  of  the  large  lymph  spaces  which  lie  under  the  skin  of 
the  frog,  A  Pravaz  syringe,  such  as  is  used  in  practical 
medicine,  may  be  used  for  the  injection.  On  examining  a  drop 
of  the  blood,  a  considerable  number  of  the  colorless  cells  will 
now  be  seen  to  ,be  stuffed  ("  gef littert ").  We  shall  afterwards 
return  to  this  matter. 

Some  preparation  is  necessary  in  order  to  count  the  numbers 
of  both  kinds  of  cells.  The  test  blood  must  naturally  be 
spread  out  into  the  thinnest  layer,  and  the  space  to  be  surveyed 


232  SECTION    ELEVENTH. 

divided.  An  eye-piece  micrometer  with  a  small  number  of 
quadratic  fields  fulfils  this  object.  In  consequence  of  the 
sparseiiess  of  lymph-cells  in  normal  human  blood  (0.5  to  2-3 
per  thousand),  and  likewise  in  mammalia,  it  is  necessary  to 
count  a  large  number  of  blood  corpuscles  in  order  to  obtain 
even  a  tolerably  accurate  result.  One  should  not  stop  under 
10-15,000. 

The  fluid  of  the  blood,  the  so-called  plasma,  appears,  as  a 
rule,  entirely  clear  like  water,  and  free  from  all  elementary 
forms,  and  therefore  is  not  an  object  of  microscopic  examina- 
tion. As  a  result  of  an  exuberant  reception  of  fat  in  the  blood, 
the  unsaponified  fat  of  the  chyle  (see  below,  at  this  fluid)  may 
appear  in  it  in  the  condition  of  the  finest  division,  in  the  form 
of  dust-like  molecules. 

It  was  formerly  hoped  that  the  microscopist  might  discover 
changes  in  the  form  of  the  blood-cells  in  disease,  and  in  this 
way  be  able  to  promote  pathological  physiology  as  well  as 
diagnosis.  These  beautiful  dreams  have  not,  in  general,  been 
fulfilled.  However  various  its  composition  may  be,  the  blood 
presents  the  same  microscopic  appearance.  It  is  also  to  a  cer- 
tain degree  the  case,  that  even  with  regard  to  the  normal  life 
of  the  blood  a  considerable  obscurity  still  prevails, — that  we 
have  but  an  extremely  incomplete  conception  of  the  new  for- 
mation and  disappearance  of  the  cells. 

However,  although  nothing  of  importance  is  to  be  perceived 
in  the  endosrnatic  changes  inform  of  the  colored  blood-cells, 
which  have  been  here  and  there  described  in  processes  of 
disease,  and  just  as  little  in  the  shreds  of  the  loosened  epithe- 
lium of  the  vessels,  the  microscope  has  nevertheless  afforded  us 
an  interesting  glimpse  of  two  pathological  processes  of  our 
fluid  ;  we  mean  the  so-called  leucaemia  and  melanoemia. 

The  former,  coinciding  with  an  increase  in  volume  of  the 
spleen  and  often,  at  the  same  time,  of  the  lymphatic  glands, 
although  but  seldom  caused  by  enlargement  of  the  latter  organs 
alone,  leads  to  a  constant  increase  in  the  number  of  colorless 
cells  in  the  blood,  so  that  finally  the  alteration  of  the  blood  no 
longer  remains  concealed  from  the  naked  eye.  A  drop  of  such 
blood  (obtained  by  pricking  the  point  of  the  finger  with  a 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  233 

needle)  shows,  together  with  the  colored,  a  considerable  number 
of  colorless  blood-corpuscles.  This  may  proceed  to  such  an 
extent  that  to  three  colored  blood-corpuscles  there  will  be  one 
or  even  two  colorless  ones,  and  in  certain  cases  the  number  of 
the  latter  variety  of  cells  will  be  greater  than  that  of  those  con- 
taining hsematin.  Transition  forms  of  both  kinds  of  cells  may 
also  be  met  with  (Klebs,  Eberth). 

In  malignant  forms  of  intermittent  fever  the  enlarged  spleen 
has  been  seen  to  have  a  blackish  appearance.  The  microscope 
shows,  as  a  cause  of  this  change  of  color,  granulated  lymphoid 
cells,  often  of  considerable  extent,  and  which  contain  within 
them  granules  of  the  black  pigment.  Passing  out  through  the 
splenic  vein,  they  become  mixed  with  the  blood  and  are  seen  in 
this  fluid  when  it  is  subjected  to  microscopic  examination.  In 
consequence  of  their  size  they  produce  obstructions  in  certain 
capillary  districts,  especially  in  the  brain  and  liver. 

Embryonic  blood  is  to  be  examined  in  the  same  manner. 
The  warmable  stage  is  to  be  used  when  it  is  desired  to  follow 
the  very  rapid  progress  of  the  division  of  the  nucleated  colored 
cells.  The  instability  of  these  cells  is,  moreover,  very  great,  so 
that  one  may  often  be  misled  by  artificial  products. 

Recklinghausen  communicated  a  singular  discovery  to  us  a 
few  years  ago.  After  a  series  of  days  one  may  see  the  lym- 
phoid cells  become  transformed  into  red  blood-corpuscles, 
in  blood  taken  from  the  frog,  if  one  understands  preserving  its 
vitality. 

For  this  purpose  the  blood  is  to  be  received  in  a  glazed  por- 
celain dish,  which  is  to  be  placed  in  a  large  glass  vessel,  the  air 
in  which  is  to  be  daily  renewed,  and  kept  constantly  moist. 
After  twenty-four  hours  the  coagulation  gives  place  to  a  process 
of  liquefaction ;  a  few  days  later,  island-like  collections  of  con- 
tractile lymphoid  cells  have  become  formed;  after  11-21 
days  one  may  recognize  the  first  of  the  new-formed  blood-cor- 
puscles. Frog's  blood  may  be  preserved  in  this  way  for  thirty- 
five  days  without  decomposition  taking  place. 

By  means  of  an  electrical  discharge  the  colored  blood-cor- 
puscles are  rendered  corrugated,  at  first  with  coarse,  then  with 
fine  indentations.  These  processes  afterwards  disappear,  and 


234  SECTION    ELEVENTH. 

the  "blood- corpuscle  becomes  transformed  into  a  smooth  bor- 
dered globule,  which  finally  undergoes  discoloration  (Rollett). 

The  living  blood-cells  of  man  and  the  mammalia  undergo  a 
very  singular  alteration  (fig.  88)  when  exposed  to  a  temperature 
of  52°  C.  on  the  hot  stage,  represented  in 
fig.  66.  A  number  of  deep  indentations  ra- 
pidly take  place,  which  very  soon  become 
constrictions,  causing  the  formation  of  glo- 
bules on  the  surface  of  the  cell.  These  are 
either  separated  at  once  or  continue  for  a 
time  to  be  connected,  by  means  of  a  long, 
slender  pedicle,  to  the  remainder  of  the  cell 
body  (a).  The  strangest  appearances  are  thus 
n  blood-  caused,  such  as  bead-like  rods,  globules  with 

cells  heated  to  52"  0.  .       '  °     r  , 

projections  like  handles,  etc.  When  these 
fragments  become  separated  they  commence  the  most  lively 
molecular  movement  (Beale,  M.  Schultze). 

The  treatment  of  the  blood-corpuscles  with  chemical  reagents 
is  indispensable  for  the  accurate  investigation  of  their  structure, 
and  is  a  very  good  exercise  for  the  beginner,  especially  if  the 
large  nucleated  cells  of  the  naked  amphibia  are  used  in  the 
place  of  the  small  non-nucleated  corpuscles  of  human  and  mam- 
malial  blood. 

Distilled  water  is  used  to  cause  them  to  swell  (fig.  89,  a). 
•The  bright  central  portion  disappears  at  once  and  a  uniformly 
yellowish  structure  is  seen  which  rapidly  loses  its  color,  and 
which,  hi  rolling,  permits  its  globular  form  to  be  recognized. 
In  this  way  the  granulated  nucleus  may  be  rendered  dis- 
tinct in  the  blood-cells  of  fish,  amphibia,  and  birds.  Many 
watery  solutions  in  a  condition  of  extreme  dilution  exert  a 
similar  effect.  For  comparison,  it  is  useful  to  treat  in  a  similar 
manner  the  large  nucleated  blood-cells  of  the  first  three  classes 
of  vertebrates.  In  order  to  obtain  them  in  a  shrivelled  condi- 
tion (fig.  89,  J),  it  is  only  necessary  to  leave  a  drop  of  blood 
uncovered  on  a  slide  for  a  few  minutes,  in  which  case  the 
familiar  corrugated  and  indented  forms  make  their  appearance. 
A  very  small  drop  of  blood,  taken  from  the  living  body  by 
pricking  with  a  fine  needle,  not  unfrequently  presents  this  in- 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  235 

dented  appearance  of  the  cells  on  the  glass  slide  at  once.  "We 
can  obtain  a  similar  effect  by  means  of  numerous  concentrated 
solutions,  such  as  those  of  salt,  sugar,  and  gum. 

If,  on  the  contrary,  we  rapidly  dry  the  blood-corpuscles  on  a 
glass  slide,  we  have  the  appearance  represented  by  fig.  89,  c,  a 
form  in  which  the  blood-corpuscles  may  be  very  well  preserved 
as  a  permanent  preparation. 


Fi'pr.  80.  a.  Human  blood-cells  under  the  action  of  water;  6,  in  evaporating  blood ;  c,  in  a  dried 
condition ;  d,  in  coagulated  blood  ;  e,  rouleaux-like  arrangement. 

Other  reagents  dissolve  its  substance,  and  in  this  way  destroy 
the  cell.  Diluted  acids  produce  this  effect,  likewise  weak  solu- 
tions of  the  alkalies.  Although  concentrated  solutions  of  the 

c5 

latter  cause  the  blood-corpuscles  to  swell,  they  do  not  destroy 
them,  even  after  acting  on  them  for  hours.  A  saturated  solu- 
tion of  potash  is,  as  Donders  found,  an  excellent  medium  for 
rendering  the  cells  of  dried  blood  again  visible. 

Many  materials  have  a  coagulating  effect  on  the  cell  substance 
of  the  blood-corpuscles.  Among  these  are  to  be  enumerated  alco- 
hol, concentrated  chromic  acid,  sublimate,  and  other  metallic  salts. 

In  defibrinated,  but  also  very  generally  in  a  drop  of  freshly 
removed  blood,  one  may  observe  the  familiar  joining  together 
of  the  colored  cells  with  their  broad  surfaces,  the  so-called 
rouleau  formation  (fig.  89,  c).  This  arrangement  is  missed 
only  in  the  more  distended  and  globular  cells  of  the  blood  in 
the  splenic  and  hepatic  veins.  • 


236  SECTION    ELEVENTH. 

In  order  to  ascertain  the  appearance  of  coagulated  blood,  one 
may  either  allow  a  drop  of  blood  to  coagulate  on  the  slide,  or 
the  finest  possible  section  may  be  taken  from  a  clot.  The  cells 
will  then  be  seen  to  be  embedded  in  a  homogeneous  layer  of 
fibrin  which  has  the  appearance  of  folds  or  filaments  (fig. 
89,  d). 

Indifferent  fluids  are  necessary  in  the  examination  of  blood 
extravasations,  for  the  proper  estimation  of  the  condition  of  the 
cells. 

The  origin  of  fresh  clots  of  blood,  treated  in  the  same  manner, 
may  be  ascertained  by  microscopic  analysis.  One  will  be  able, 
for  example,  to  distinguish,  by  their  form  and  size,  the  cells  of 
the  blood  of  birds  from  those  of  human  blood,  etc.,  and  in  this 
way  to  detect  impostors.  It  is  difficult,  and  in  many  cases 
impossible,  to  render  a  decision  in  old  masses  of  dried  blood. 
The  character  of  a  spot  which  is  suspected  to  be  blood  may,  on 
the  contrary,  be  determined  in  the  most  certain  manner  by 
means  of  Teichmann's  hsemine  test,  a  subject  to  which  we  shall 
again  refer. 

The  accessories  mentioned  under  lymph  and  chyle  are  to  be 
used  when  the  further  investigation  of  the  colorless  blood-cells 
is  necessary. 

It  is  only  under  certain  circumstances  that  the  colored  blood- 
cells  can  be  tinged  with  carmine,  but  this  may  be  readily  accom- 
plished with  anil  in  red ;  still,  nothing  is  to  be  gained  thereby. 

The  above-mentioned  process  of  rapid  drying  may  be  very 
advantageously  employed  for  preserving  blood-cells  permanently 
as  preparations  for  a  collection.  I  have  in  my  possession  pre- 
parations of  the  blood  of  different  animals  which  are  more  than 
20  years  old,  and  which  leave  nothing  to  be  desired. 

The  first-mentioned  Pacinian  fluid  is  adapted  for  mounting 
the  cells  of  human  blood  moist ;  Pacini's  second  mixture  (see  p. 
213)  serves  for  the  colorless  cells  of  the  blood. 

Solutions 'of  sublimate,  as  formerly  mentioned  (p.  215),  have 
also  been  recommended.  Ilarting  employs  for  the  blood-cells 
of  man  and  the  mammalia,  1  part  of  bichloride  of  mercury  to 
200  of  water,  for  those  of  birds  1  to  300,  for  those  of  the  frog 
1  to  400.  Remak  employed,  for  embryonic  blood-cells,  very 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND   PUS.  237 

weak  solutions  of  the  bichromate  of  potash,  of  chromic  acid 
(0.03  per  cent.),  and  of  sublimate  (0.03  per  cent.). 

"We  should  make  ourselves  responsible  for  a  considerable  defi- 
ciency were  we  to  omit  mentioning  the  various  crystallizations 
which  are  to  be  obtained  from  the  colored  blood-corpuscles. 
This  subject  has  in  our  day  been  zealously  and  persistently 
investigated ;  but,  regarded  from  a  scientific  point,  this  matter 
leaves,  even  yet,  much  to  be  desired. 

From  the  blood  of  man  and  the  various  vertebrated  animals, 
including  birds,  one  may  obtain  the  coloring  substance  of  the 
cells  in  a  crystalline  condition  ;  the  so-called  blood  crystals  be- 
ing formed.  This  substance  has  been  called  haemoglobin  or 
haemato-crystalline.  Many  investigations  have  been  instituted 
concerning  these  remarkable  structures  by  Funke,  Lehmann, 
Kunde,  Teichmann,  Rollett,  Bojanowski,  and  others  ;  Reichert 
having  previously  discovered  in  them  a  crystallized,  colorless, 
albuminous  body. 

According  to  the  general  acceptation,  the  blood-crystals  pre- 
sent various  forms,  such  as  prisms,  tetrahedes,  hexagonal  tables 
and  rhomboids.  The  prismatic  form  is  regarded  as  the  most 
common,  and  appears  in  man  and  most  of  the  mammalia  (fig. 
90,  #,  c),  together  with  which,  rhomboidal  tables  (b)  may  also  be 
met  with.  Tetrahedal  (but  not  regular)  crystals  are  formed  by 
the  haemoglobin  of  the  Guinea-pig  (d)  and,  as  is  generally  al- 
leged, of  the  mouse ;  rhomboidal  crystals  are  met  with  in  the 
hamster  (e\  hexagonal  tables  (f)  in  the  squirrel  (and  mouse  ?).* 

"With  regard  to  the  manner  of  producing  blood-crystals,  we 
limit  ourselves  to  the  following  examples  : — 

They  are  to  be  prepared  for  microscopic  examination  accord- 
ing to  Funke's  directions.  A  drop  of  blood  is  to  be  placed  on 
the  glass  slide,  where  it  is  left  in  contact  with  the  air  for  several 
minutes.  A  drop  of  water  is  then  to  be  added,  and  the  whole 
breathed  on  a  few  times.  A  covering-glass  is  now  placed  over 
it,  and  evaporation  allowed  to  take  place  slowly,  whereby  the 
crystallization  is  promoted  by  the  action  of  the  light. 


*  In  reality,  nearly  all  blood  crystals  belong  to  the  rhomboidal  system,  only 
those  of  the  squirrel  to  the  hexagonal. 


238 


SECTION    ELEVENTH. 


Bojanowski  recommends  the  following  procedure :  Blood,  as 
it  escapes  from  the  vein,  or  still  better,  such  as  is  taken  from 
the  vessels  of  a  dead  animal ,  is  to  be  kept  in  a  vessel  for  2-4 
days  in  a  cool  place,  whereby  the  coagulum  begins  to  dissolve 
into  a  thick,  fluid,  dark  red  to  blackish  mass.  A  drop  of  this 
fluid  is  to  be  placed  on  the  slide,  covered,  and  exposed  to  the 
light  for  a  few  hours.  The  crystals  may  then  be  seen.  If  the 
blood  which  is  to  be  used  for  this  purpose  is  too  thick,  the  drop 
may  be  very  suitably  diluted  with  distilled  water. 


Fip.  90.  Blood -crystals  of  man  and  several  of  the  mammalia,  a,  blood  crystals  from  human 
venous  blood  ;  ft,  from  the  splenic  vein  :  c.  crystals  from  the  blood  of  the  heart  of  the  cat ,  d,  from 
the  jugular  vein  of  the  Guinea  pig;  e,  from  the  hamster ;  and/,  from  the  jugular  of  the  squirrel. 

Hollett,  who  has  also  produced  a  very  valuable  work  on  blood 
crystals,  makes  use  of  a  blood,  the  cells  of  which  have  been 
destroyed  by  freezing  and  remelting.  The  formation  of  crystals 
also  readily  takes  place  in  electrified  blood,  and  in  that  of  the 
Guinea-pig  (which  of  all  kinds  of  blood  crystallizes  the  most 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS. 


239 


readily)  this  is  often  so  rapid  as  to  appear  "  as  though  the  crys- 
tals had  been  struck  out  with  the  spark."  Blood  from  which 
the  gases  have  been  pumped  out  is  also  well  adapted  for  ob- 
taining hsemato-crystalline. 

Chloroform  with  the  access  of  air  also  causes  the  formation 
of  our  crystals  (Bottcher). 

Lehmaim  has  taught  us  how  to  produce  crystals  of  the  hydro- 
chlorate  of  haematin  (figs.  91,  92). 


Fig.  91.    Crystals  of  hydro-chlorate  of 
haeinatin. 


Fig.  92.    Crystalline  forma  of  the  hydro- 
chlorate  of  haematin. 


They  are  to  be  obtained  by  treating  fresh  blood  or  large  spots 
of  blood  which  are  two  days  old  with  alcohol  containing  oxalic 
acid  and  ether  (1  part  alcohol,  4  parts  ether,  and  -fa  of  a  part  of 
oxalic  acid).  Preserved  in  well-closed  bottles,  the  crystals  are 
gradually  precipitated  from  the  fluid  ;  the  process  is  hastened  by 
the  addition  of  chloride  of  calcium  which  has  become  liquefied 
by  exposure  to  the  air.  Where  the  separation  takes  place  more 
rapidly  the  crystals  are  more  of  the  acicnlar  form,  as  represented 
at  the  lower  part  of  fig.  91 ;  if  more  slowly,  either  the  hexagonal 
tables  of  fig.  91  or  the  crystals  which  are  represented  in  fig.  92. 
They  appear  to  have  a  long  and  narrow  laminated  shape  and 
twisted  one  or  two  times  on  their  long  axis.  They  are  very 


240  SECTION   ELEVENTH. 

thin,  of  a  brownish  and  brownish-green  translucency,  as  repre- 
sented at  the  upper  half  of  fig.  92.     If  allowed  to  remain  for 
some  time  in  the  mixture  of  alcohol  and  ether  in  which  they 
were  precipitated,  wre  have  produced,  as  another  modification, 
the  crystals  given  in  the  lower  half  (to  the  right)  of  the  figure, 
quadratic  and  also  rhomboidal  black  tables  which,  by  more  ac- 
curate examination,  prove  to  be  flat  rhomboidal  octahedrons. 
Teichmann  has  produced  crystals  of  the  same  modification  of 
haematin    and    called    them    haemin. 
The  coloring  matter  of  the  blood,  in 
its  different  conditions,  is  to  be  dis- 
solved by  means  of  hot  concentrated 
acetic   acid,  so  as  to  become   separ- 

\^  ated  in  a  crystalline  form  as  it  cools. 

f    y  A  condition  of  the  precipitation  is  the 

S  ~*A         "&*  ^U    Presence  °f  alkaline  chlorates.     The 
^  hseinin  crystals  obtained   present  the 

appearances   represented  in   fig.    93, 
as    rhomboidal    tables    of    a    black- 
rig.  93.  crystals  of  haemin.         ish-brown,  sometimes    blacker,   more 

rarely  light-brown  color. 

By  proper  treatment  the  crystals  with  which  we  are  at  pres- 
ent occupied  may  be  obtained  from  blood  which  is  either  fresh 
or  decomposed  by  putridity,  from  that  which  is  dried,  and  even 
from  the  oldest  blood-stains.  Ilaemin  is  therefore  of  great  im- 
portance in  a  forensic  point  of  view,  and  forms  the  best  means 
of  recognizing  the  origin  from  blood  of  a  suspected  stain.* 

If  it  be  desired  to  produce  a  somewhat  larger  number  of 
crystals,  a  quantity  of  blood  is  to  be  boiled  for  about  a  minute 
or  two  in  the  10-20  fold  volume  of  glacial  acetic  acid  and 
filtered.  As  the  fluid  cools  it  becomes  somewhat  cloudy,  and  a 
blackish  sediment  is  deposited,  consisting  of  crystals  of  haemin. 
For  the  momentary  demonstration  the  following  process  is  to  be 
employed : — A  drop  of  blood  is  to  be  rapidly  dried  on  the  slide, 


*  With  regard  to  the  value  of  the  haemin  crystals  in  a  forensic  point  of  view, 
as  well  as  the  possibility  of  mistaking  other  substances  for  them,  see  the  ar- 
ticle of  Buchner  and  Simon  (Virchow's  Arch.,  Bd.  17,  S.  50). 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  241 

over  the  spirit  lamp,  and  then  scraped  to  a  powder  with  the 
point  of  a  knife.  About  10-20  drops  of  anhydrous  acetic  acid 
is  to  be  added  and  allowed  to  boil  a  few  times,  the  slide  is  then  to 
be  set  aside  for  a  few  moments.  A  drop  of  blood,  diluted  with 
15-20  drops  of  glacial  acetic  acid  and  placed  in  a  watch-glass  on 
the  stove,  also  forms  the  crystals  in  question,  as  the  fluid  eva- 
porates. They  are  likewise  deposited  when  blood  is  mixed  with 
an  excess  of  concentrated  acetic  acid.  After  a  few  days  a  film, 
consisting  of  these  crystals,  is  formed  on  the  surface  ;  after  the 
removal  of  this  a  second  is  formed,  and  so  on. 

In  order  to  obtain  the  hsemin  crystals  from  an  old  blood-stain, 
the  stained  substance  is  isolated  and  placed  in  a  test-tube,  glacial 
acetic  acid  is  then  poured  over  it  and  boiled  for  a  few  minutes, 
it  is  then  filtered  into  a  watch-glass.  This  fluid,  to  which  more 
acid  is  to  be  added,  is  then  exposed  to  evaporation  in  a  warm 
place.  I  am  indebted  to  the  kindness  of  Dr.  A.  Schmidt,  of 
Frankfort,  for  a  preparation  of  hsemin  which  was  obtained  from 
a  pocket-handkerchief  saturated  with  blood  at  Sand's  execution. 

Ilsemin  crystals,  in  consequence  of  their  durability,  may  be 
very  readily  preserved  as  microscopic 
preparations.     They  may  be  mounted 
dry  or  in  glycerin. 

In  old  blood  extravasations,  for  ex- 
ample, those  of  the  brain,  in  hemor- 
rhagic  infarctions  of  the  spleen,  in 
obliterated  veins,  in  the  corpus  luteum 
crystals  of  hsematoidin,  discovered  by 
Virchow,  are  formed  (fig.  94) ;  they 
differ  from  the  bilirubin  which  occurs 
in  the  bile.  They  generally  occur  in 
small  rhomboidal  prisms  of  a  lively 
orange  or  ruby-red  color,  with  dark  carmine-red  borders  and 
edges.  Together  with  these,  amorphous  precipitates  of  hsematoi- 
din,  in  granular  and  globular  masses,  will  be  frequently  met  with. 

.Staedeler  succeeded,  by  treating  the  ovaries  of  the  cow  with 
chloroform,  or  with  sulphuret  of  carbon,  in  obtaining  uncom- 
monly large  crystals  (fig.  95)  of  our  coloring  material,  some  of 
them  measuring  even  0.2'".      These  make  their  first  appcar- 
16 


242 


SECTION    ELEVENTH. 


ance  under  the  microscope  as  acute-angled,  three-sided  tables, 
with  one  convex  side  (#),  although  this  convex  side  may  also  be  re- 
placed by  two  direct  lines,  so  that 
deltoid  tables  (I)  result.  Two 
such  tables  usually  become  united 
like  twins,  their  convex  sides  com- 
ing in  contact  with  or  overlap- 
ping each  other,  and  melting  to- 
gether (bj  r).  In  this  manner  are 
formed  the  rhomboidal  tables, 
usually  designated  as  hsematoidin 
(fig.  94).  As  a  rule,  there  are  at 
first  indentations  in  the  place 
of  the  obtuse  angle  of  the  rhom- 
bus, which  gradually  become 

Fig.  95.   Very  large  crystals  of  hajmatoi-    „..     ,  ...        °  J 

din  obtained  from  the  ovarium  of  the  cow  tilled  Out  («,  a).  JN  ()t  UllireQUent- 
by  treating  with  chloroform. 

ly   two   other   crystals    also   be- 
come united  with  the  first  two  individual  crystals,  so  that  four 
rayed   stars  now  appear  (e).      By  the  filling   out  of  their  re- 
entering  angles  four-sided  tables 
(f,  g)  are  formed,  which,  by  in- 
creasing their  thickness,  finally 
assume  the  appearance  present- 
ed by  dice  when  seen  somewhat 
from  the  side  (Staedeler). 

Preparations  of  hsematoidin 
may  be  readily  and  well  pre- 
served dry  or  lying  in  glycerine. 

We  have  reserved  the  most  in- 
teresting portion  of  this  section 
for  the  end ;  the  movement  of 
the  blood  in  the  living  animal 

Fig.  96.  The  blood-current  in  the  web  of  the 

body  is  still  to  be  discussed.          ***•  a' the  Tessel  with  the  colored  blood- 

»  corpuscles  in  the  axial  port  on,  and  the  color- 

In  order  to  see  the  blood  flow-  Jf s  ce!!8  inA  thuat  1)°™io"  ?f  ^e  71I7en*  near 

the  walls  ;  6,  the  epithelial  cells  of  the  tissue. 

ing  through  the  vessels  of   the  » 

living  animal  (fig.  96)  it  is  necessary  to  select  transparent  lo- 
calities. The  web  of  the  hindfoot  of  the  frog,  the  transparent 
tail  of  the  larvae  of  the  frog  and  salamander,  the  embryos  of  fish 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    ATO)    PUS.  243 

and  small  recently-hatched  fish  are  exceedingly  well  adapted 
for  the  first  observations. 

If  the  larvae  of  frogs  are  used  the  anterior  portion  of  the  body 
is  to  be  enveloped  with  a  strip  of  moistened  blotting-paper,  and 
the  tail,  after  being  moistened  with  water,  is  to  be  covered  with 
a  thin  covering-glass.  If  the  frog  itself  is  to  be  used,  a  strip 
of  wood  or  cork  containing  a  glass  window,  5  or  6  lines  in  size, 
which  goes  over  the  hole  in  the  stage,  is  to  be  employed.  The 
frog  is  to  be  wrapped  in  a  moistened  rag,  or  enclosed  in  a  small 
linen  bag,  and  secured  to  the  wooden  strip.  The  web  is  to  be 
expanded  by  means  of  pins  (but  without  too  great  tension),  and, 
after  being  moistened  Avith  water,  a  thin  covering-glass  is  to  be 
placed  over  it ;  it  is  best  to  have  the  latter  three-cornered  or 
rhomboidal  in  shape.  Instead  of  the  simple  strip  of  wood,  a 
small  table  may  be  very  suitably  arranged  for  supporting  the 
frog.  Frog-holders  have  been  invented  for  this  purpose  ;  they 
are  quite  superfluous.  If  one  has  the  remarkable  muscle-poi- 
son, woorara,  at  one's  disposal,  it  is  only  necessary  to  inject  a 
minimal  quantity  of  the  same  under  the  skin  to  render  our 
animal,  after  a  few  hours,  immovable  for  a  considerable  time — 
one  or  two  days — so  that  the  simplest  arrangement  is  then  all 
that  is  necessary.  An  object  slide  of  considerable  size,  on  which 
is  cemented  a  small,  thick,  right-angled  plate  of  glass  with  a 
cork  ring  surrounding  it,  for  fastening  the  toes  to,  is  then  suffi- 
cient. For  tadpoles,  the  anterior  portion  of  the  body  may  be 
simply  enveloped  in  a  strip  of  blotting-paper,  and  the  tail,  with 
the  addition  of  water,  covered  with  a  thin  glass.  Object-slides 
with  long,  four-sided  excavations,  as  proposed  by  F.  E.  Schulze, 
and  represented  in  section  by  our  fig.  97,  are  very  well  adapted 

b  a/ 

IvSSSSSS^. 


Fig.  If?.  Object-slide  for  the  larvae  of  irogs  and  salamanders. 

for  the  examination  of  the  larvae  of  naked  amphibiae  and  young 
fish.  The  head  goes  under  the  edge  #,  and  the  tail  of  the  ani- 
mal lies  on  the  inclined  surface  b.  The  whole  is  to  be  covered 
with  a  thin  glass.  The  apparatus  may  be  very  readily  con- 
structed by  cementing  four  pieces  of  glass  on  to  a  slide. 


244  SECTION   ELEVENTH. 

In  examining  the  circulation  only  very  weak  lenses  should 
be  employed  at  first,  in  order  to  obtain  a  more  considerable 
view  of  the  relations  of  the  currents.  Then  proceed  to  the  use 
of  higher  powers,  with  which  the  details,  especially  in  the  capil- 
lary vessels,  are  to  be  investigated.  It  is  unnecessary  to  remark 
that  the  apparent  rapidity  of  the  current  is  in  this  way  very 
much  increased.  In  reality,  this  is  by  no  means  considerable 
in  the  capillary  districts.  A  corpuscle  of  frog's  blood  passes 
through  the  fifth  or  fourth  part  of  a  line  in  a  second. 

The  colored,  in  contradistinction  to  the  colorless  elements  of 
the  blood  of  the  adult  animal,  are  without  any  vital  contractibil- 
ity,  as  may  be  best  learned  by  j  ust  these  observations  of  the  cir- 
culation of  the  frog ;  it  is  only  possible  to  recognize  here  cer- 
tain passive  changes  of  the  so  flexible  and  elastic  cells. 

A  discovery  recently  made  concerning  an  anomalous  condi- 
tion of  the  blood  cells  of  the  mammalia  is  of  interest.  So  long 
as  they  remain  in  the  circulation  they  but  rarely  appear  in  the 
above-mentioned  form  of  the  passive  condition,  but  rather  pre- 
sent the  greatest  variety  of  shapes,  so  that  that  which  in  the 
frog  formed  an  exception  has  here  become  the  rule.  Even  this 
only  concerns  a  passive  condition,  for  as  soon  as  they  become 
quiet  they  again  resume  the  familiar  cup  shape  (Rollett). 

The  mesentery  of  the  frog  is  to  be  recommended  for  studying 
the  condition  of  the  circulation  during  the  process  of  inflamma- 
tion (Cohnheim).  Take  a  sufficiently  large  plate  of  glass, 
cement  to  this  a  small  glass  disk  nearly  a  line  in  thickness  and 
of  about  12  mm.  diameter,  and  around  the  latter  a  narrow 
(about  1  mm.  broad)  cork  ring.  An  opening  is  to  be  made 
through  the  abdominal  walls  on  the  left  side  of  a  frog  which 
has  been  paralyzed  with  woorara,  the  mesentery  is  to  be  drawn 
out,  and  the  loop  of  intestine  fastened  with  a  few  fine  needles 
to  the  cork  ring.  The  simple  irritation  of  the  air  produces  the 
inflammation,  and  if  the  mesentery  be  protected  from  drying 
the  process  may  be  studied  for  many  hours. 

Small  mammalia,  maintained  in  a  condition  of  narcosis  by 
means  of  ether  or  chloral,  may  also  be  used  for  such  investiga- 
tions, although  with  the  assistance  of  manifold  complicated 
apparatuses  (Strieker  and  Sanderson). 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  245 

But  let  us  return  to  the  mesentery  of  our  frog !  Dilatation 
of  the  vessels  (at  least  of  the  capillaries)  gradually  takes  place, 
sluggishness  of  the  current  follows,  and  numerous  lymphoid 
cells  collect  at  the  colorless  peripheral  portion  of  the  veins. 
The  lymphoid  cells  begin  to  migrate  through  the  uninjured 
walls  of  the  latter  and  of  the  capillaries ;  colored  corpuscles 
also  pass  through  the  capillaries  into  the  neighboring  tissues. 
After  a  half  or  a  whole  day,  when  the  surface  of  the  mesentery 
is  covered  by  a  dull  grayish  layer  of  pus  cells,  these  remarkable 
phenomena  have  commenced  in  full  force.  The  pus  cells  have 
therefore  come  from  the  blood-vessels  (Cohnheim).  If  a  finely 
granular  coloring  material  has  been  previously  injected  into 
one  of  the  lymph  sacs  of  the  animal,  a  part  of  these  cells  will 
contain  coloring  matter. 

If,  on  the  contrary,  the  circulation  be  arrested  by  ligating  the 
crural  vein,  the  blood  corpuscles  will  be  seen  to  be  pressed 
closely  together  in  the  vessels  of  the  web  of  our  animal.  Here, 
also,  there  is  a  passive  escape  of  colored  blood-cells.  It  is  al- 
most impossible,  on  the  contrary,  for  the  lymphoid  corpuscles 
to  manifest  their  vital  contracting  power,  in  consequence  of  the 
compression  exerted  by  the  overloaded  condition  of  the  vessel. 
Here  their  active  emigration  generally  fails,  or  is  but  very 
slight. 

A  similar  emigration  of  the  lymphoid  cells  also  takes  place 
in  normal  life.  The  movable  cells,  which  wander  through  the 
spaces  in  the  connective  tissue,  are  to  be  reckoned  among 
these. 

Cohnheim's  beautiful  observations,  which  confirm  the  older 
views  of  A.  AValler,  possess  an  extraordinary  range  and  have 
rapidly  called  forth  an  entire  literature.  Opinions  are  still  un- 
defined-with  regard  to  this  subject.  Do  all  these  migratory 
cells  and  pus  corpuscles  originate  in  the  blood,  and,  having  mi- 
grated, are  they  incapable  of  further  increase  by  division  ?  May 
not  pus  cells  proceed  from  the  cellular  elements  of  the  connec- 
tive tissue  ?  Finally,  are  these  emigrants  capable  of  being 
transformed  into  other  tissue  elements?  The  latter  is  not  to  be 
doubted ;  and  very  many  observers  have  affirmed  the  division 
of  the  lymphoid  cells,  as  well  as  their  origin  from  the  cells  of 


246  SECTION   ELEVENTH. 

the  connective  tissue.    "We  shall  again  refer  to  some  of  these 
points. 

2  and  3.  The  examination  of  lymph  or  chyle  is  also  very  easy  ; 
only  some  little  preparation  is  necessary  for  obtaining  the  mate- 
rial. In  order  to  obtain  lymph,  a  mammal  is  to  be  killed  by 
a  blow  on  the  head,  and,  after  carefully  opening  the  thorax,  a 
ligature  is  to  be  applied  to  the  ductus  thoracicus.  The  lym- 
phatic vessels  will  be  found  to  be  swollen  even  after  a  quarter 
of  an  hour,  and  the  distention  is  increased  by  waiting  for  a 
longer  time.  If  the  animal  has  been  killed  several  hours  after 
a  plentiful  meal  containing  fat,  the  lacteals  become  filled  with 
a  milk-white  fluid  and  stand  out  in  the  most  beautiful  manner. 
With  small  herbivorous  animals,  for  instance,  rabbits,  an  elastic 
catheter  may  be  introduced  into  the  oesophagus,  and  a  consider- 
able quantity  of  milk  injected  through  this  into  the  stomach. 
After  an  interval  of  several  hours  the  lacteals  will  be  found 
magnificently  filled. 

The  lymphatic  or  lacteal  vessels  are  then  to  be  ligated  in 
pieces  about  one  inch  in  length,  a  ligature  being  applied  at 
each  end,  and  the  vessel  carefully  separated  from  the  connective 
tissue.  The  separated  vessels  are  to  be  cleaned  by  washing  in 
water  and  again  dried,  after  which  they  are  to  be  opened  over 
a  watch-glass  or  a  slide. 

If  the  lymph-corpuscles  are  desired  for  rapid  demonstra- 
tion only,  the  necessary  material  may  be  obtained  by  prick- 
ing any  lymphatic  gland. 

7        /     *       J  ^n  lymPn  an(l  chyle  we  find,  by  2- 

®O  ©    ^P      ^^  fold  enlargement,  the  character- 
s  +        s    istic    cells   (fig.   98),   the    same   with 

(?)  ®  which  we  have  already  become  famil- 

*ar  *n  the  blood  as   colorless   blood- 


® 


e,      ^        >f      ^       corpuscles.     When  examined  in  their 
a  °  *  natural  fluid,  these  structures  do  not, 

rig.  98  Lymph-ceils.  as  a  ril]e?  show  anything  further  than 

a  granulated  globule  of  varying  size  (fig.  98  1-4).  If  this  ex- 
amination is  made  with  the  necessary  precautionary  measures,  the 
same  change  of  form  of  the  cell  may  here  be  found,  as  an  evi- 
dence of  a  vital  contractibility,  which  we  have  mentioned 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS.  247 

above  (p.  231)  concerning  the  colorless  elements  of  the 
blood. 

In  order  to  demonstrate  further  the  manner  of  its  organiza- 
tion (nucleus  and  cell-body),  water  or  extremely  diluted  acetic 
acid  may  be  used.  (Stronger  acids  soon  dissolve  the  envelope 
of  the  cell  and  its  contents.)  These  changes  are  represented  in 
the  figure  from  5  to  13.  The  ammoniacal  solution  of  carmine, 
fuchsine,  and  aniline-blue  may  be  used  for  staining. 

Innumerable  fat  molecules,  in  the  condition  of  the  finest 
division,  occur  in  the  milk-white  chyle,  as  the  cause  of  its  color. 
These  atoms  require  a  strong  (4-600  fold)  enlargement. 

For  their  preservation,  the  mixture  mentioned  at  p.  214 
(No.  3),  consisting  of  sublimate  (1),  salt  (2)  and  water  (300),  is  to 
be  recommended  ;  Pacini's  second  fluid  may  also  be  employed. 

4.  Mucus  does  not  require  any  preparation.  It  may  be 
either  scraped  with  the  blade  of  a  knife  from  the  surface  of  the 
mucous  membrane,  or  it  may  be  obtained  from  the  nose  or 
respiratory  organs,  etc.  A  moderate  quantity  is  to  be  placed 
on  the  slide.  Uncommonly  tough  masses  of  mucus  are  to  be 
divided  with  the  scissors. 

The  microscopic  examination  (with  a  2-400  fold  enlarge- 
ment) shows  us  a  somewhat  irregular  constitution.  We  meet 
with  an  extremely  variable  quantity  of  the  same  colorless 
granulated  cells  which  have  just  been  referred  to  as  colorless 
blood-corpuscles,  and  also  as  elements  of  the  lymph  and  chyle, 
the  "  lymphoid  cells."  The  name  of  mucous  corpuscles  has 
been  given  them,  only  in  the  cavity  of  the  mouth  these  struc- 
tures are  called  salivary  corpuscles.  In  the  latter  place,  coin- 
ciding with  the  thinner  and  more  watery  fluid,  granular  move- 
ments are  observed  in  the  interior  of  the  cells.  Conformably 
to  this,  a  cessation  of  these  movements  may  be  produced  by  the 
addition  of  concentrated  solutions  ;  they  may  also  be  incited  in 
all  other  lymphoid  cells  by  removing  them  to  a  very  watery 
neighborhood  (0.  Richardson).  Together  with  these,  is  also 
associated  an  extremely  variable  quantity  of  the  desquamated 
cells  of  the  existing  epithelial  formation,  and  likewise  the 
separat3d  cells  of  the  various  mucous  glands.  In  consequence 
of  its  viscid  nature,  there  are  very  generally  air-bubbles  impri- 


248 


SECTION   ELEVENTH. 


soned  within  the  mucus.  Furthermore,  there  are  also  very 
many  extraneous  admixtures  to  be  seen  ;  as  the  remains  of  food, 
for  example,  fibres  of  meat,  grains  of  starch,  particles  of  dust, 
threads  of  fungus,  and  many  others.  The  recognition  of  the 
latter  ingredients  requires  a  certain  amount  of  practice. 

I  have  tried  a  number  of  conserving  fluids  for  preserving 
mucus,  but  thus  far  without  any  notable  results. 

5.  The  same  granulated  cell  formation — we  know  it  already 
— occurs  finally  as  an  element  of  a  pathological  fluid,  the  pus ; 
it  receives  the  name  of  pus  cell,  or  pus  corpuscle. 

A  fluid  may  be  recognized  as  pus,  not  by  its  constitution,  but 
rather  by  the  number  of  its  cells.  • 

Pus  cells  are  the  extravasated  colorless  blood  corpuscles  which 
have  collected  at  the  point  of  irritation.  The  formation  of 

these  structures  in  the  interior  of 
epithelial  cells  (fig.  99),  where,  by 
the  destruction  of  the  mother  cell, 
the  contained  cell  was  set  free, 
was  also  formerly  assumed  (Tle- 
mak,  Buhl,  Eiiidfleisch).  These 
observations  are  certainly  cor- 
rect. 1^  the  thin,  watery  secre- 
tion of  the  mucous  membrane  in 
the  first  days  of  a  catarrh  be  ex- 
amined, one  may  perceive,  according  to  the  variety  of  the  epi- 
thelium, together  with  free  pus  corpuscles,  ordinary  desquama- 
ted epithelial  cells,  and  others  with  contents  such  as  are  re- 
presented in  the  figure  mentioned.  But  the  explanation  must 
be  very  different.  These  structures  which  lie  before  us  are 
those  vagabonds  of  the  body,  the  wandering  cells,  which  have 
penetrated  from  the  tissue  of  the  mucous  membrane  into  the 
epithelial  cells. 

We  shall  afterwards  speak  of  a  possible  and  probable  forma- 
tion of  pus  cells  from  the  connective-tissue  cells.  Naturally  a 
collection  of  the  pus  cells  never  takes  place  on  the  surface  of  a 
mucous  membrane.  They  may  afterwards  be  found  scattered 
through  the  tissue  of  the  interior  of  an  organ  (for  instance,  in 
the  inflamed  cornea)  also  ;  they  may  then  collect  in  great  num- 


Pus  cells  of  man  and  mammalia 
lying  in  the  interior  of  epithelial  cells. 


BLOOD,    LYMPH,    CHYLE,    MUCUS,    AND    PUS. 


249 


bers  beneath  the  epithelium,  finally  force  off  the  epithelial  cov- 
ering and  thus  cause  an  erosion  and  an  ulcer,  or,  when  in  inter- 
nal parts,  they  may  cause  the  formation  of  an  abscess  in  conse- 
quence of  the  melting  down  of  the  neighboring  tissues. 

Pus  corpuscles  are  naturally  to  be  examined  in  the  same  man- 
ner as  the  elements  of  lymph  and  chyle. 

The  vital  changes  of  form  of  pus  cells  have  become  known  to 
us  within  a  few  years.  If  after  about  two  days,  as  the  result  of 
the  application  of  an  irritant  to  the  cornea  of  a  frog,  its  humor 
aqueus  becomes  cloudy,  the  latter  will  show  a  number  of  ener- 
getically contracting  proteus-like  cells  (fig.  100).  Thin,  thread- 


Fig.  100.  Contractile  pus  cells  from  the 
humor  aqucns  of  the  fropr.  of-A',  vital  changes 
of  the  cell :  6,  a  pus  corpuscle  with  granules  of 
carmine  in  its  interior ;  /,  the  dead  cell. 


Fig.  101.    Acid  pus  from  an  old  abscess  of 
the  upper  part  of  the  thigh. 


like  processes  may  give  the  pus  corpuscle  a  radiated  appearance 
(«),  which  may  afterwards  change  to  an  irregular  indentated 
form  (b).  Not  unfrequently  the  processes  become  further  rami- 
fied, and,  by  the  meeting  and  blending  of  neighboring  branches 
(<?),  reticular  processes  result  (c  d).  Long,  extended  forms  some- 
times show  themselves  temporarily  (e  i).  A  reception  of  neigh- 
boring small  molecules,  such  as  carmine,  within  the  interior  of 
the  cell  may  also  be  observed  (Z»). 

The  pus  cells  of  man  and  the  mammalia  also  possess  a  sim- 
ilar vital  changeability  of  form. 

A  similar  alteration  of  shape  may  be  recognized  when  these 


250  SECTION   ELEVENTH. 

cells  are  in  the  spaces  of  a  more  compact  tissue ;  as  for  instance 
in  the  cornea.  Here,  it  is  true,  the  cells  generally  appear 
stretched  out  and  rendered  narrow,  being  constrained  by  the 
limited  space. 

Such  a  locality  also  presents  the  best  opportunity  to  follow 
the  above-mentioned  progression,  or  wandering  of  these  con- 
tractile structures  through  the  passages  alluded  to.  This  is  not 
unfrequently  quite  energetic.  However,  it  is  not  even  neces- 
sary to  have  an  inflamed  organ,  for  the  same  lymphoid  cell,  with 
the  same  variation  and  the  same  progression,  also  occurs  in  the 
normal  cornea. 

The  most  conservative  treatment,  the  avoidance  of  positive 
fluid  media,  of  pressure,  and  of  evaporation  are  absolutely  ne- 
cessary, if  one  desires  to  witness  the  remarkable  phenomena 
mentioned. 

The  intermingling  of  other  cells,  such  as  epithelium  and 
blood-corpuscles,  is  recognized  without  trouble. 

Many  transformations  take  place  in  pus,  which  we  cannot 
at  present  discuss  further.  We  will  only  mention  one  of  these, 
the  acid  fermentation  of  pus.  It  precedes  the  alkaline  decom- 
position, and  brings  with  it  anatomical  and  chemical  alterations. 

When  the  reaction  is  somewhat  acid  the  nuclei  of  the  pus 
cells  become  visible.  The  neutral  fats  are  decomposed,  and 
free  fatty  acids  make  their  appearance  in  a  crystalline  form. 
Such  are  shown  in  our  fig.  101,  partly  in  the  shape  of  needles, 
and  partly  in  pointed,  lamellated  masses ;  together  with  these 
are  the  rhomboidal  plates  of  cholesterin. 

A  mixture  consisting  of  1  part  sublimate,  1  part  salt,  and 
300  water,  is  used  for  preserving  them.  Another  preservative 
fluid  has  been  recommended  for  causing  the  nuclei  to  appear : — 
1  part  sublimate,  1  part  acetic  acid,  and  300  water  (p.  214). 


Section 


EPITHELIUM,  NAILS,  HAIR. 

THE  various  so-called  corneous  tissues  of  the  human  body 
require  similar  methods  of  examination,  in  consequence  of 
the  resemblance  in  their  chemical  constitution,  and  may  there- 
fore be  very  appropriately  discussed  togsther. 

1.  Under  the  name  of  epithelium  are  understood  the  cover- 
ings of  crowded  cells  which  are  presented  by  the  various  sur- 
faces of  the  body,  partly  as  simple  layers,  partly  as  stratified 
layers.  According  to  the  form  of  the  cells,  the  pavement  or 
flattened  epithelium,  consisting  of  flattened  elements,  is  dis- 
tinguished from  the  cylindrical,  in  which  the  cells  are  long 
and  narrow.  Furthermore,  we  have  as  modifications  the 
ciliated  epithelium,  in  which  the  surface  of  the  cell  is 
covered  with  very  fine  cilia  which  vibrate  during  life,  and 
the  pigmented  epithelium,  containing  within  the  cell  granules 
of  black  pigment,  the  so-called  melanine. 

Layers  are  in  general  found  only  in  flattened  epithelium. 
The  cylindrical  forms  a  single  layer,  which,  it  is  true,  is  also 
the  case  with  many  coverings  of  pavement-shaped  cells. 


Fig.  102.     Flattened  epithelium  of  the  mucous  Fig.  103.     Cylindrical  epithelium  of 

membrane  of  the  mouth  of  man.  the  largo  intestine  of  the  rabbit. 

The  adjacent  wood-cuts  may  serve  to  represent  the  various 
forms  of  epithelium.  Fig.  102  presents  the  flattened  epithe- 
lium of  the  cavity  of  the  mouth;  fig.  103,  the  cylindrical 


252 


SECTION    TWELFTH. 


variety  from  the  intestinal  canal,  while   fig.  104   shows   the 
ciliated,  and  fig.  105  the  pigmented  form. 


Fig.  104.    Various  forms  of  the 
ciliated  cells  of  mammalia. 


Fig.  105.  Pigmented  pavement  epithe- 
lium (so-called  polyhedral  pigment  cells) 
of  the  sheep. 


It  is  scarcely  necessary  to  remark,  that  only  stratified  epithe- 
lium is  visible  to  the  naked  human  eye,  while  such  cellular 
coverings,  when  they  consist  of  but  few  layers  or  only  a 
single  one,  are  only  rendered  apparent  by  the  aid  of  the 
microscope.  Thus,  the  densest  epithelial  covering,  that  of  the 
external  skin,  was  known  in  olden  times,  while,  for  instance, 
a  knowledge  of  the  simple  cell  coverings  of  the  surfaces  of 
serous  membranes  and  of  the  vessels  is  an  acquisition  of  a 
more  recent  period. 

In  order,  therefore,  to  obtain  the  first  view  of  the  epithelial 
cells  of  a  surface,  it  is  sufficient  to  separate  the  cells  from  their 
natural  connections  with  the  clean  blade  of  a  scalpel,  and  to 
transfer  them  with  a  little  fluid  to  the  slide.  One  will  then 
meet  in  part  with  isolated  structures,  in  part  with  whole  shreds 
of  connected  cells. 

That  which  is  here  artificially  accomplished  is  in  many  cases 
performed  by  nature.  The  pressure  and  friction  which  many 
surfaces  of  the  body  undergo,  disconnects  the  epithelium  from 
its  basis.  In  this  manner  are  separated  the  cells  of  the  epi- 
dermis, and  those  of  the  various  mucous  membranes.  Old 
cells  fall  off  spontaneously,  as  it  is  said.  The  mucous  cover- 
ings of  the  various  mucous  membranes  exhibit  in  varying 
abundance  the  desquamated  epithelium  of  the  membrane 
in  question,  as,  by  way  of  example,  we  find  in  the  mucus 
of  the  mouth,  the  oldest  and  largest  cells  of  the  flattened 


EPITHELIUM,    NAILS,    HAIR.  253 

epithelium ;  in  that  of  the  nose  and  air-passages,  the  ciliated 
cells ;  in  that  of  the  intestinal  canal,  the  cylindrical  epithelium. 

However,  much  of  the  epithelium  of  the  body  appears  to  be 
of  a  more  enduring  nature ;  it  is  less  rapidly  renewed,  and  we  do 
not  notice  that  spontaneous  desquamation.  As  examples,  we 
have  the  flattened  cells  which  cover  the  posterior  surface  of  the 
cornea,  the  pigmented  pavement  epithelium  of  the  eye,  etc. 
Moreover,  the  cells  of  which  these  coverings  are  composed  prove 
to  be  very  delicate  when  acted  upon  by  reagents,  and  do  not 
resist  decomposition  for  any  length  of  time. 

The  cells  of  all  unstratified  epithelium  are  seen  to  be  composed 
of  soft  and  readily  alterable  albuminous  matters.  Hence  the 
greatest  freshness  of  the  tissue  is  necessary  for  their  examination. 
It  would  be  a  piece  of  folly  to  look  for  them  in  a  cadaver  which 
is  several  days  old.  In  this  case  they  would  be  either  entirely 
destroyed,  or  only  fragments  of  them  wrould  be  found. 

Simple  pavement  epithelium,  as  it  occurs  on  the  posterior 
surface  of  the  cornea,  011  the  serous  membranes,  and  the  inner 
surfaces  of  the  vessels,  is  to  be  obtained  by  scraping  and  exa- 
mined with  strong  (400-fold)  magnifying  power.  The  isolated 
cells  are  frequently  so  pale  that,  even  with  considerable  shading 
of  the  field,  it  is  desirable  to  have  them  tinged.  Solutions  of 
carmine,  hsematoxylin,  aniline  blue  or  aniline  red  may  be  used 
for  this  purpose.  We  would  especially  recommend  the  latter  as 
coloring  instantly,  and  not  exerting  any  alterative  effect.  Very 
dilute  acetic  acid  may  be  used  to  render  the  nuclei  more  distinct, 
although  there  is  rarely  any  occasion  for  its  use.  It  is  some- 
what difficult  to  obtain  a  simultaneous  view  of  these  simple 
tesselated  cells  and  their  basement  membrane.  Thin  vertical 
sections  of  the  previously  dried  tissue  will  rarely  lead  to  the 
desired  results,  as  the  cells,  as  a  rule,  become  separated  by  the 
reapplication  of  moisture.  A  characteristic  view  may  be  more 
readily  obtained  from  parts  which  have  been  hardened  in  chro- 
mic acid  or  alcohol.  In  the  vascular  system  the  free  border  of 
a  valve  is  a  favorable  locality  for  the  recognition  of  its  epithelial 
covering.  A  view  of  the  epithelium  of  the  serous  membranes 
may  be  obtained  by  carefully  separating  a  shred  of  the  mem- 
brane from  its  bed  and  forming  a  fold  of  its  free  surface.  If 


254 


SECTION    TWELFTH. 


the  posterior  surface  of  the  cornea  be  energetically  scraped, 
inverted  pieces  of  the  membrane  of  Descemet  with  its  epithelial 
covering  may  sometimes  be  seen  in  the  preparation. 

Hecklinghausen's  method  of  impregnation  with  silver  (see  p. 
160)  is  also  an  excellent  means  of  demonstrating  the  contours  of 
pale  epithelial  cells.  The  boundary-lines  become  extremely 
distinct,  even  after  a  slight  action  of  the  silver  solution,  as  the 
precipitation  takes  place  in  the  intercellular  or  cement  substance 
first,  and  the  cell  cavities  remain  free.  If  it  be  desired,  the  nu- 
clei may  be  afterwards  stained  with  carmine.  The  epithelium 
appears  with  such  distinctness  in  the 
small  blood  and  lymphatic  vessels  that 
the  course  of  these  vessels  may  be  re- 
cognized the  same  as  in  an  injected 
preparation.  Even  in  the  cavernous 
passages  or  the  sinuses  of  the  lymphatic 
system,  an  epithelial  covering  may  in 
this  way  be  made  visible  throughout 
(fig.  IOC,  a,  I). 

We  shall  afterwards  learn  what  re- 
markable information  the  silver  treat- 
ment has  recently  furnished  concerning 
the  structure  of  the  capillaries. 

Indifferent  fluids  are  to  be  recom- 
mended rather  than  water  as  media  for 

the  examination  of  epithelium.  I  have  not,  as  yet,  been  able 
to  preserve  these  structures  very  well  when  mounted  moist, 
but  silver  preparations  keep  very  well,  especially  in  Canada 
balsam. 

The  pigmented  pavement  epithelium  (the  polyhedral  pigment 
cells  of  a  former  time),  which  occurs  in  the  eye,  and  cove  re  the 
choroid  with  a  simple,  the  ciliary  processes  and  the  posterior 
surface  of  the  iris  with  a  stratified  layer,  is  to  be  examined  in 
the  same  manner.  Shreds  of  the  same  may  be  readily  removed 
with  a  scalpel  or  a  brush,  and,  when  carefully  spread  out  with 
the  brush,  they  present  the  beautiful  mosaic  (fig.  105)  to  view. 
Such  shreds,  when  folded,  present  a  side  view  of  the  cells. 
Chromic  acid  preparations  and  dried  eyes  may  also  be  used  for 


Fig.  106.  Cylindrical  epithelium 
from  the  surface  of  lymphatic 
canals  after  impregnation  with  sil- 
ver, a,  elongated ;  b,  broader  mo- 
saic. 


EPITHELIUM,    NAILS,    HAIE.  255 

demonstrating  the  epithelial  formations  of  which  we  are  at 
present  speaking. 

If  one  desire  to  observe  the  molecular  movement  of  the  black 
pigment  granules,  it  is  only  necessary  to  make  pressure  with  the 
covering-glass  in  order  to  liberate  the  cell  contents,  which  then 
begin  their  movements  in  the  water.  In  this  case  it  is  advanta- 
geous to  use  the  strongest  objectives,  so  as  to  magnify  the  move- 
ments of  the  granules  as  much  as  possible. 

The  highest  modern  magnifying  powers  appear  to  indicate  a 
crystalline  constitution  of  these  molecules. 

They  may  be  successfully  mounted  in  glycerine,  Miiller's 
fluid,  and  Canada  balsam. 

The  methods  of  investigating  cylindrical  and  ciliated  epithe- 
lium are  also  the  same. 

Scraping  with  the  blade  of  a  knife  furnishes  ample  views  of 
these  cells,  isolated  and  hanging  together 
in  shreds  (fig.  107).  Cylindrical  epi- 
thelium may  be  most  advantageously 
examined  several  hours  after  death,  as 
they  are  then  more  readily  separated 

J  .  i/lvT      r         „  Fig.    107.     Cylindrical  epithe- 

IrOin    their    parent    tiSSUeS.       JNot     Unire-      li»«n  from  the  small  intestine  of 

the  rabbit.    «,  Side  view  of  the 

quently,  groups  of  cells  have  their  free    celH  with  ,the  thickened  and 

-1  •*  7  r  somewhat  elevated  seam,  which 

Sill-faces     turned     towards     US,     and     thus      is  Permeated  by  porous  canals; 

6,  view  of  the  cells  from  above, 

present,  seen  in  bird's-eye  perspective,    whereby  the  a^rtures  of  the 

£  >  J        r         r  i      porous    canals  appear  as  small 

the  familiar,  elegant  mosaic  (I).  points. 

The  dried  mucous  membrane  may  be  used  in  order  to  obtain 
a  view  of  the  cylindrical  epithelium  with  its  attachments.  Wet 
preparations,  that  is,  such  as  have  been  hardened  by  means  of 
chromic  acid,  bichromate  of  potash,  and  alcohol,  are  much  more 
suitable.  If  the  part  was  sufficiently  fresh  when  immersed,  the 
epithelial  covering  will  be  beautifully  seen  on  thin  sections,  made 
with  a  sharp  razor.  The  appearances  are  rendered  much  more 
distinct  by  tingeing  with  carmine. 

Indifferent  fluids,  tingeing,  and  the  application  of  dilute 
acetic  acid  are  generally  employed  for  the  further  investigation 
of  this  structure. 

An  animal  killed  during  the  digestion  of  fat  may  be  used  for 
demonstrating  the  passage  of  molecules  of  chyle  through  the 


256 


SECTION   TWELFTH. 


cylindrical  epithelial  cells  of  the  small  intestine  (with  this  point 
the  previous  section,  Chyle,  is  to  be  compared). 


Fig.  108.  The  same  cells.  At  a  the  seam  is  lifted  up  by  the  action  of  water  and  slight  pressure ; 
at  6,  appearance  in  the  natural  condition  :  at  c  a  portion  of  the  thickened  border  destroyed ;  at 
d  e  f  it  has  become  resolved  into  isolated  rods  or  prismatic  pieces  by  the  prolonged  action  of  water. 

The  thickened  seam  which  occurs  on  the  free  surface  of  the 
cylindrical  cells  of  the  small  intestines,  etc.,  has  more  recently 
been  subjected  to  an  accurate  investigation,  and  found  to  be 
permeated  by  fine  vertical  lines  (compare  fig.  108,  also  107). 
Most  investigators  of  the  present  time  accept  these  lines  for  the 
optical  expression  of  fine  passages  which  pass  through  the  seam, 
so-called  porous  canals,  an  opinion  which  is  also  entertained  by 
the  writer  of  these  lines.  Strong  magnifying  powers,  especially 
immersion  systems,  are  requisite  for  the  recognition  of  the 
subtile  textural  relations.  The  animal  may  be  used  immediately 
after  being  killed,  but  it  is  better  to  expose  the  intestine  to  the 
air  for  several  hours,  which  will  facilitate  the  separation  of  the 
cells.  Intestinal  mucus,  blood  serum,  weak  solutions  of  chromic 
acid,  solutions  of  salt  (2  per  cent.),  and  of  phosphate  of  soda.  (5 
per  cent.),  may  be  used  as  media.  The  addition  of  water  has 
a  destructive  effect  on  the  seam.  The  individual  pieces  separ- 
ate from  each  other  in  the  direction  of  the  vertical  lines  ;  not 
unfrequently,  the  appearance  is  presented  as  if  the  cell  had  a 
border  of  cilia  (d  ef),  which  was  also  the  opinion  of  the  first 
observers  (Gruby  and  Delafond).  A  similar  effect  is  produced 
by  maceration  for  about  six  hours  in  phosphate  of  soda  (5  per 
cent.),  or  the  so-called  strong  acetic  acid  mixture  of  Moleschott 
(Coloman  Balogh). 


EPITHELIUM,    NAILS,    HAIR.  257 

All  that  was  said  concerning  the  cylindrical  cells  also  holds 
good  for  the  examination  of  ciliated  epithelium  ;  only,  one 
should  commence  as  soon  as  possible  after  death,  and  make  use 
of  indifferent  media,  as  water  usually  attacks  the  fine  cilia  and 
soon  causes  them  to  fall  off.  On  the  contrary,  a  strong  solution 
of  potash,  from  28  to  40  per  cent.,  preserves  them  very  well,  as 
Schultze  ascertained. 

Tingeing  with  aniline  red  is  very  useful ;  it  may  be  rapidly 
done,  and — in  the  frog  at  least — does  not  cause  the  ciliary 
movements  to  cease. 

Mounting  in  strongly  diluted  glycerine  is  to  be  recommended 
for  preserving  cylindrical  epithelium,  especially  that  which  has 
been  hardened  by  means  of  alcohol.  I  have  not  as  yet  suc- 
ceeded in  keeping  the  ciliated  cells,  with  the  preservation  of 
their  cilia,  for  any  length  of  time. 

Before  proceeding  to  the  lamellar  epithelium  we  will  allude 
to  the  most  remarkable  vital  phenomenon  of  the  tissue,  the 
vibratory  or  ciliary  motion. 

Since  the  vibratory  phenomenon  outlasts  the  death  of  the 
creature  and  the  separation  of  the  cell  from  its  natural  connec- 
tions for  a  very  unequal  length  of  time,  in  the  individual  animal 
groups,  it  is  of  the  greatest  importance  to  make  a  suitable  selec- 
tion. Mammalia  and  birds,  in  which  the  movements  of  the 
cilia  very  rapidly  cease,  are  therefore  to  be  avoided  in  the  first 
examinations.  The  naked  amphibia,  salamanders  and  frogs,  are 
best  adapted ;  the  larger  size  of  their  cilia  also  constitutes  a 
second  and  not  unimportant  advantage.  Many  of  the  inverte- 
brates, such  as  the  river  muscles  of  the  genera  imio  and  ano- 
donta,  as  well  as  the  genus  cyclas,  which  have  on  their  gills  a 
covering  of  ciliated  cells  with  splendid  long  hairs,  are  exceed- 
ingly well  qualified  for  this  purpose.  By  using  very  powerful 
lenses  one  may  also  obtain  a  view  of  an  important  textural  con- 
dition in  the  vibratory  cells  of  the  intestine  of  the  river  muscle. 
The  cilia  are  the  continuations  of  fine  protoplasma  filaments  of 
the  cell-body  (Eberth,  Marchi). 

The  fluid  media  are  of  great  importance  in  the  study  of  the 
vibratory  movements.  It  is  asserted  in  general  that  everything 
which  does  not  affect  the  cell  substance  chemically  allows  the 
17 


258  SECTION    TWELFTH. 

ciliary  movement  to  continue;  everything,  on  the  contrary, 
which  alters  its  molecular  condition  terminates  the  movements 
once  for  all. 

The  indifferent  natural  fluids  should  therefore  be  preferred 
to  all  others.  Blood  serum  in  the  first  line,  also  liquor  amnii,  vi- 
treous fluid,  milk,  and  even  urine  form  excellent  fluid  media. 
Iodine  serum  appears  to  be  very  serviceable  ;  bile  exerts  an  un- 
favorable effect.  The  addition  of  pure  water  increases  the 
activity  of  the  vibrations  for  a  short  time,  to  cause  them  to  cease 
all  the  sooner.  An  alkaline  reaction  of  the  fluid  media  is  to  be 
denoted  as  favorable,  acid  as  unfavorable.  Oxygen  has  an  ex- 
citing, carbonic  acid  a  paralyzing  effect  (Kiihne).  A  moderate 
increase  of  temperature  increases  the  activity ;  a  higher  tempera- 
ture, which  destroys  the  life  of  the  protoplasma,  exerts  the  same 
effect  on  the  allied  ciliary  movement  (Roth). 

In  order  to  commence  the  first  observations,  a  piece  is  to  be 
cut  from  a  membrane  covered  with  ciliated  cells  (for  example, 
the  mucous  membrane  of  the  gums,  or  the  pericardium  of  the 
frog),  serum  is  to  be  added,  and  the  membrane  folded  in  such  a 
manner  that  its  cellular  surface  forms  the  free  border  of  the 
fold.  In  order  to  avoid  pressure,  which  might  dislodge  the 
slippery  mucous  membrane  or  force  the  folds  apart,  the  frag- 
ment of  a  somewhat  thick  covering-glass  is  to  be  laid  in  the 
fluid  and  the  preparation  covered ;  or  the  specimen  may  be 
made  to  adhere  to  the  under  surface  of  the  covering-glass  and 
placed  in  the  moist  chamber  (fig.  64).  Blood  cells  which  float 
in  the  fluid  form  a  valuable  addition  (they  may  be  replaced  by 
particles  of  coal,  granules  of  indigo,  and  carmine). 

If  the  examination  be  made  with  a  low  power,  a  movement, 
a  vibration,  as  the  phenomenon  has  been  appropriately  named, 
is  recognized  at  the  margin  of  the  fold.  The  corpuscles  will 
now  be  seen  driven  forward  in  a  rapid  current,  which  is  always 
in  a  definite  direction ;  and  if  the  fold  shows  hills  and  valleys, 
one  may  see  some  of  the  corpuscles  driven  forward  and  then 
suddenly  thrown  back  again.  The  older  observers  were  led  to 
think  of  electrical  attraction  and  repulsion.  When  the  pheno- 
menon begins  to  be  paralyzed  and  the  magnifying  power  is 
somewhat  increased,  the  movement  becomes  more  distinct  and 


EPITHELIUM,    NAILS,    HAIR.  259 

appreciable.  The  regular  and  simultaneous  vibration  of  the 
cilia  now  appears  like  an  undulating  border,  like  the  flaring  of 
a  candle,  or  the  rippling  of  a  clear  rivulet  in  the  sunlight.  If 
we  follow  the  vibratory  movement  for  a  still  longer  time,  and 
at  the  same  time  increase  the  magnifying  power,  a  moment 
arrives  in  which  the  individual  cilia  may  be  distinctly  seen  to 
vibrate,  but  only  one  direction  of  the  excursion  can  be  recog- 
nized at  first.  Already  the  blood-corpuscles  are  driven  past 
more  slowly,  and  we  are  able  to  perceive  how  a  cell  is  driven 
down  into  a  valley  and  then,  by  means  of  the  microscopic  whirl- 
pool, it  undergoes  the  above-mentioned  repulsion.  If  the  ex- 
amination be  still  further  prolonged,  the  number  of  the  indivi- 
dual vibrations  becomes  less  and  less  ;  we  can  now  see  both  of 
the  excursions  of  the  cilia,  and  a  moment  soon  arrives  when 
small  bodies  suspended  in  the  water — in  our  example,  the  blood 
cells — present  only  irregular  fluctuating  movements  in  front  of 
the  ciliated  margin.  Finally,  the  cessation,  the  expiration  of 
the  movements  appear.  Over  a  certain  space  all  the  cilia  are 
stiff  and  motionless.  There  may  still  be  a  vibratory  movement 
in  the  neighborhood  for  a  short  time  ;  finally,  this  ceases  also. 

It  was  a  beautiful  discovery  of  Yirchow's,  that  the  ciliary 
movement  which  has  but  just  ceased  may  be  again  called  to  life 
for  a  short  time.  Yery  dilute  solutions  of  potash  and  soda  are 
necessary  for  this  purpose. 

If  the  isolated  piece  of  mucous  membrane  is  not  too  large, 
one  may  watch  it  as  it  is  slowly  driven  from  its  position  by  the 
united  labor  of  its  innumerable  cilia. 

The  ciliary  movement  may  also  be  examined  in  still  another 
manner— and  this  is  to  be  especially  recommended  for  more 
accurate  investigations  with  powerful  lenses.  The  epithelium  is 
to  be  separated  in  shreds  by  scraping  somewhat  energetically  the 
surface  of  the  exposed  mucous  membrane.  Here  one  may  at 
first  recognize  a  few  groups  of  cells  engaged  in  the  most  active 
rotatory  movements,  also  isolated  disconnected  cells  with  vibra- 
ting cilia,  etc. 

"With  regard  to  the  number  of  vibrations  which  take  place  in 
a  given  space  of  time,  the  cilia  move  so  rapidly  at  first  that  an 
estimation  having  any  degree  of  accuracy  is  not  to  be  thought  of. 


260  SECTION    TWELFTH. 

It  has  been  assumed  that  there  were  a  few  hundred  vibrations 
to  the  minute,  but  this  is  an  uncertain  valuation,  and  is  really 
much  too  low.  Afterwards  it  becomes  more  and  more  easy  to 
count  them. 

The  manner  in  which  the  cilia  vibrate  is  by  no  means  always 
the  same.  Purkinje  and  Valentin,  who  investigated  the  ciliary 
movements  in  the  most  thorough  manner  a  number  of  years 
ago,  distinguish  four  varieties  of  movements:  the  hook-like, 
the  funnel-shaped,  the  oscillating,  and  the  undulatory.  The 
first  variety  is  regarded  as  being  by  far  the  most  frequent. 
According  to  Engelmann's  beautiful  investigations :  on  the  con- 
trary, the  ciliated  cell,  when  thoroughly  unimpaired,  only  exhi- 
bits the  undulatory  motion.  All  other  forms  of  vibration  are 
caused  by  the  cilia  having  become  stiff  and  motionless  in  certain 
places. 

The  examination  of  the  ciliary  movement  in  mammalia  and 
birds  requires  the  rapid  preparation  of  the  tissue  immediately 
after  the  death  of  the  animal,  the  addition  of  its  blood,  iodine 
serum,  and  the  hot  stage.  Sometimes,  in  spite  of  all  haste,  one  is 
too  late,  in  other  cases  the  vibration  continues  to  be  lively  for  sev- 
eral minutes.  A  few  cases  are  known  in  which,  long  after  death, 
in  the  bodies  of  mammalia  which  have  become  quite  cold,  the 
liveliest  ciliary  movements  were  still  perceptible  to  the  aston- 
ished eye.  I  have  myself  observed  such  a  case,  years  ago. 

Human  ciliated  cells  with  well-preserved  cilia  can  only  be 
observed  in  a  cadaver  which  is  quite  fresh ;  those  with  moving 
cilia  may  be  obtained  under  certain  circumstances  from  the 
living.  If  one  bores  with  a  feather  (the  beard  of  which  has 
been  cut  short)  in  the  upper  part  of  the  nose,  ciliated  cells  which 
are  still  living  may  sometimes  be  found  in  the  mucus  which  is 
thus  rubbed  off.  They  may  be  more  readily  obtained  by  examin- 
ing the  thin  watery  secretion  from  the  nasal  or  respiratory 
mucous  membranes  at  the  commencement  of  a  severe  acute 
catarrh.  In  such  cases,  together  with  regular  shaped  ciliary 
cells,  abnormal  examples  will  also  be  found  in  great  numbers, 
some  which  are  swollen,  others  which  present  a  more  globular 
form,  and  within  which  may  be  recognized  a  granular  body,  a 
pus  cell  (fig.  99,/,  p.  248).  (Eindfleisch.) 


EPITHELIUM,    NAILS,    HAIR. 


261 


Fig.  109.  So-called  stach- 
el  or  riff  cells,  a,  from 
the  deeper  layers  of  hu- 
man epidermis ;  ft,  cell 
from  a  papillary  tumor 
of  the  human  tongue 
(observed  by  Sehultze). 


All  of  the  varieties  of  simple  epithelium  which  have  thus  far 
been  mentioned  consist  of  relatively  alterable  soft  cells. 

It  is  different  with  the  stratified  flattened  epithelium,  as  met 
with  on  many  mucous  membranes,  and  most 
strongly  developed  as  a  covering  to  the  ex- 
ternal integument.  In  these  cases  it  is  only 
the  deeper  layers  of  younger  cells  which 
still  retain  a  similar  soft  and  readily  alter- 
able constitution.  As  it  appears,  these  are 
to  a  great  extent  joined  together  in  a  very 
peculiar  manner  (Sehultze).  The  surfaces 
of  these  membraneless  structures  (fig.  109, 
a,  I)  are  everywhere  covered  with  points, 
prickles,  and  ridges  which  insinuate  them- 
selves between  those  of  the  neighboring  cells 
"  like  the  bristles  of  two  brushes  when 
pressed  together,"  so  that  the  name  stachel 
and  riif  cells  is  quite  appropriate. 

The  older  layers  of  this  variety  of  epithe- 
lium show,  on  the  contrary,  cells  with  smoother  surfaces,  which, 
in  becoming  flattened  and  spread  out,  are  also  chemically 
altered.  They  consist  of  a  much  more  resistant  modification  of 
albumen ;  they  are  cornified,  as  it  is  said.  The  methods  of 
examination  are  therefore  to  be  modified. 

It  is  self-evident  that  the  various  layers,  even  to  the  youngest, 
may  be  brought  to  view  by  scraping,  and  at  the  same  time  one 
of  the  ordinary  methods  of  tingeing  may  be  advantageously 
employed,  especially  for  the  youngest  cells.  By  the  use  of 
reagents,  and  especially  of  a  weak  acid,  we  may  recognize  a 
considerable  power  of  resistance  in  the  older  scale-like  epithelial 
cells,  while  those  which  are  younger  are  soon  attacked  and  only 
their  nuclei  remain. 

Maceration  in  iodine  serum  is  to  be  especially  recommended 
for  demonstrating  and  isolating  the  stachel  cells  (see  above,  p. 
124). 

Drying  and  hardening  in  alcohol  are  employed  for  obtaining 
transverse  sections  through  a  whole  stratum  of  epithelium. 
The  first  method  is  in  general  to  be  preferred  for  the  external 


262  SECTION   TWELFTH. 

integument,  the  last  for  the  mucous  membranes.  Weak  tingeing 
with  carmine  and  subsequent  washing  in  water  acidulated  with 
acetic  acid  yields  excellent  preparations.  The  cell  nuclei 
may  be  recognized  even  in  the  most  superficial  layers  of  the 
epithelium  of  mucous  membranes,  while  the  quite  colorless 
non-nucleated  scales  of  the  cornified  epidermis  appear  in  the 
most  beautiful  manner  above  the  deeper  layers  which  are 
stained.  Impregnation  with  silver  may  also  be  used  here  with 
good  results. 

There  is  no  medium  which  renders  such  good  service  in  the 
examination  of  the  stratified  flattened  epithelium  as  alkalies, 
especially  potash  and  soda.  By  the  use  of  these  reagents  the 
cells  may  be  made  to  assume  a  sometimes  lower,  sometimes 
higher  degree  of  distention  ;  they  may  be  isolated,  their  nuclei 
destroyed  while  their  membranes  are  preserved ;  and  finally, 
they  may  be  entirely  dissolved.  The  use  of  alkaline  solutions 
is,  therefore,  of  the  greatest  value  in  the  enumeration  of  the 
superimposed  layers,  as,  on  the  other  hand,  they  reveal  the 
structural  conditions  of  the  epithelial  cells  better  than  any  other 
method. 

A  strong  solution  of  potash  or  soda  forms  a  combination  with 
the  substance  of  the  flattened  epithelium  in  question  which 
causes  the  cell  to  swell  and  which  eagerly  mixes  with  water, 
and  thus  induces  an  increasing  intumescence  till  the  cell  is 
finally  dissolved.  Concentrated  solutions  therefore  exert  a  dif- 
ferent effect  from  those  which  are  more  diluted,  and  the  quantity 
of  potash  especially  which  a  fluid  medium  contains  is  of  the 
greatest  importance. 

Moleschott,  who  has  examined  this  subject  more  accurately, 
has  instituted  a  series  of  experiments  on  this  point.  He  made 
use  of  the  dried  tissue. 

A  strong  solution  of  potash  of  35  per  cent,  induces  only  a 
moderate  distention  ;  the  cells  form  a  very  elegant  mosaic  and 
their  nuclei  are  preserved.  The  intercellular  or  cement  sub- 
stance which  unites  the  cells  is  gradually  dissolved,  the  cells 
become  isolated  and  float  about  in  the  fluid.  The  nuclei  are 
preserved  even  with  solutions  of  30  per  cent.,  but  they  are 
rapidly  attacked  by  those  which  are  weaker,  below  20  per  cent. 


EPITHELIUM,    NAILS,    HAIR. 


263 


In  order  to  cause  a  considerable  distention  of  the  cells,  to  the 
form  of  elliptical  vesicles,  the  tissue  is  to  be  placed  in  a  solution 
of  potash  of  30-10  per  cent,  for  the  space  of  about  four  hours. 


Fig.  110.  1.  Epithelial  cells :  at  a  an  unaltered  flat  cell  from  the  cavity  of  the  mouth ;  at  b-f 
the  same  variety  of  cells  after  treatment  with  caustic  soda,  some  still  with  nuclei  (6  c  d),  some 
already  without  nuclei  («/);  at  g  after  the  action  of  soda  with  the  addition  of  acetic  acid. 
2.  Epidermoid  cells :  a,  unaltered ;  ft,  at  the  commencement  of  the  soda  action ;  at  c  the  more 
prolonged  action  of  the  reagent ;  d  with  the  addition  of  acetic  acid. 

If  water  be  added  to  these  swollen  cells,  they  become  distended 
into  vesicles  which  are  as  transparent  as  glass,  and  soon  dissolve. 
Before  this,  however,  the  reduction  of  an  albuminous  matter 
(their  corneous  substance)  may  be  induced  in  the  epithelial  cells 
of  the  preparation,  by  over-saturating  the  fluid  with  acetic  acid. 
From  what  has  been  said,  the  corresponding  illustrations  of  our 
fig.  110,  which  represent  the  pavement  epithelium  of  the  cavity 
of  the  mouth  (1),  as  well  as  that  of  the  external  integument  (2) 
under  such  treatment,  must  be  intelligible. 

The  cells  are  gradually  dissolved  in  very  weak  solutions,  from 
10-5  per  cent.,  of  potash,  but  weaker  solutions,  under  5  per 
cent.,  exert  less  effect  on  this  tissue. 

Solutions  of  soda  may  also  be  employed  with  advantage,  but 
they  must  be  more  dilute. 

A  solution  of  chloride  of  gold  (0.005  per  cent.)  and  its  reduc- 


264  SECTION   TWELFTH. 

tion  oy  means  of  sulphate  of  iron  (p.  165),  has  recently  been 
recommended  by  Nathusius  for  the  cornified  tissues.  Such 
preparations  may  afterwards  be  exposed  to  the  alkalies  with 
advantage. 

For  the  examination  of  the  stratified  flattened  epithelium, 
fine  vertical  sections  of  the  tissue  which  has  been  thoroughly 
hardened  in  alcohol  or  chromic  acid  are  to  be  especially  recom- 
mended. Tingeing  with  carmine  should  also  not  be  neglected. 

The  cornified  cells  may  be  readily  mounted  in  preservative 
fluids.  Glycerine  is  to  be  used  with  stained  sections.  They 
often  make  right  handsome  preparations  when  deprived  of  their 
water  and  mounted  in  Canada  balsam. 

2.  The  tissue  of  the  nails.  In  consequence  of  their  consist- 
ence, the  nails  permit  of  sections  being  made  in  the  various  di- 
rections without  further  preparation,  but  their  elements  are 
combined  in  such  a  manner  that  one  can  see  nothing  but  a  ho- 
mogeneous tissue  which,  in  consequence  of  its  brittleness,  is  per- 
meated by  numerous  rents  and  flaws.  Heagents  which  soften 
and  dissolve  the  intercellular  substance  are,  therefore,  indispen- 
sable. Sulphuric  acid  and  alkaline  solutions  have  been  used. 
The  former,  even  concentrated,  act  but  slowly  when  cold,  al- 
though after  a  few  days  epithelial  disks  may  be  distinctly  recog- 
nized. By  boiling  they  make  their  appearance  very  rapidly, 
even  in  half  a  minute.  The  nuclei  do  not  become  sufficiently 
visible  by  this  method. 

Solutions  of  potash  and  soda  act  very  much  better,  as  was  in- 
dicated by  Kolliker  many  years  ago.  One  may  often  obtain 
yery  handsome  specimens  of  isolated  and  distended  cells,  in 
which  the  nuclear  formations  not  unf requently  stand  out  very 
beautifully,  even  without  using  solutions  of  known  strength.  A 
solution  of  potash  of  about  25-27  per  cent,  appears  to  be  suit- 
able. Weak  solutions  destroy  the  nuclei. 

A  momentary  boiling  in  a  dilute  solution  of  soda  (about 
10  per  cent.)  also  frequently  affords  very  characteristic  views. 
The  structure  of  the  nails  may  be  demonstrated  in  this  way 
almost  instantaneously.  Fig.  Ill  shows  us  the  cells  of  the 
nails  isolated  in  the  latter  manner. 

As  is  well  known,  numerous  epithelial  new  formations  occur. 


EPITHELIUM,    NAILS,    HAIE. 


265 


Cysts  and  encysted  tumors  are,  for  the  most  part,  lined  with 
pavement  cells.  Hypertrophied  growths  of  the  skin,  indurations, 
verruca  and  hornlike  excrescences  present  an  arrangement  which 


Fig.  111.  Tissue  of  the  human  nail,  in  part 
after  the  action  of  the  solution  of  soda,  a,  cells 
of  the  most  superficial  layers  in  profile ;  &,  a 
cell  seen  from  above  ;  c,  half  profile  ;  d,  a  num- 
ber of  cells  which  are  rendered  polyhedral  by 
the  pressure  of  their  neighbors ;  e,  a  cell,  the 
nucleus  of  which  is  beginning  to  disappear ;  /, 
cells  of  the  deepest  layer  (stratum  mucosum 
Malpighii) ;  at  g  one  of  these  cells  with  double 
nucleus. 

is  similar  to  the  strata  of  the  cornified  epi- 
dermis and  which  require  analogous  me- 
thods of  examination,  such  as  drying,  ver- 
tical sections,  solutions  of  potash,  etc. 
The  pearl-like  tumors  (among  which  are 
to  be  reckoned  Hassal's  concentric  bodies 
of  the  thymus)  and  the  epithelial  can-  rig.  112.  Transverse  section 

.i         ,        ,  •,!     T    T     through  a  human    hair    and  its 

cers  or  cancroids  also  have  an  epithelial  fomcie.  a,  hair;  &,  epidermis  of 

,  ,,          n      ,      .        A,         j.  «   ,  the  same;   c,  inner  and  d,  outer 

Character,    the    nrst    in    the    lOrm    OI    be-    layer  of  the  inner  root  sheath ;  e, 

„  „  ,.  oiiter  root  sheath;/,  its  peripheral 

mgn,  the    latter    in    the    lOrm    OI    malign     layer  of  elongated  cells ;   g,  struc- 

tureless  membrane  of    the    hair 
neoplasms.       Hie     preparatory      methods     sac  ;/t,  its  middle,  and  z,  external 

are  to  be  adapted  to  their  varying  con- 
sistence.    The  fresh  tissue  may  be  examined  in  part  as  fine  sec- 
tions and  picked  preparations,  in  part  after  the  use  of  harden- 
ing agents.     Tingeing  and  the  alkalies  are  also  to  be  employed. 
Nails  undergo  but  slight  changes. 

3.  Hair  and  its  tissue.  We  shall  assume  that  the  complicated 
structure  of  the  human  hair  has  already  been  learned  from  the 
text-books  on  histology. 

In  order  to  examine  the  hair  with  its  sac  and  the  most  inferior 
portion  of  its  bulb,  a  hair  of  strong  calibre  is  to  be  prepared 


266  SECTION    TWELFTH. 

from  the  skin,  or  a  piece  of  the  skin  of  the  head  which  has 
either  been  dried  in  the  air  or  hardened  by  means  of  alcohol 
may  also  be  used  with  advantage.  But  in  making  vertical 
sections,  it  is  necessary  to  keep  as  close  as  possible  to  the  direc- 
tion in  which  the  hair  passes  through  the  skin.  Transverse  sec- 
tions through  the  hair  and  all  its  coverings  (fig.  112)  may  be 
obtained  in  a  similar  manner.  Moleschott  recommends  the 
immersion  in  his  strong  acetic  acid  mixture  for  a  few  months. 

A  hair  which  has  been  slowly  drawn  out  from  the  head  may 
be  used  for  the  first  examination. 

The  root  will  often  be  found  covered  with  the  white  sub- 
stance of  the  so-called  root-sheath,  with  the  exception  of  its 
lowermost  portion,  which  has  remained  with  the  terminal  part 
of  the  bulb  in  the  follicle.  White  hairs  are  most  suitable; 
blonde  are  better  than  dark.  Water  or  glycerine  may  be  used  as 
a  medium.  Weak  powers  will  then  permit  of  the  recognition 
of  the  essential  structural  conditions. 

No  further  preparation  with  the  exception  of  strong  lenses, 
and  at  most  the  use  of  acetic  acid,  is  necessary  for  examining 
the  finer  structure  of  the  outer  root-sheath  (figs.  112  0,  113  c). 
The  inner  root-sheath  (fig.  112,  c  d)  may  be  obtained  either 
from  sections,  made  parallel  with  the  surface  of  the  skin  of 
hairy  parts  of  the  body,  or  from  hairs  which  have  been  drawn 
out  after  stripping  off  the  outer  sheath  and  removing  it  from 
the  shaft  of  the  hair.  It  may  also  be  seen  on  short  transverse  sec- 
tions, made  through  the  bulb  of  the  moistened  hair  while  lying 
on  the  slide,  and  then  picked  with  needles.  Although  the  first 
few  attempts  may  fail,  a  little  attention  and  the  use  of  strong 
lenses  will  lead  to  the  recognition  of  the  two  differently  shaped 
layers  of  cells  (figs.  112,  c  d,  113  a  5)  of  the  inner  sheath. 
The  structure  of  the  shaft  and  bulb  of  the  hair,  as  well  as  the 
epidermoid  covering,  may  even  now  be  recognized  to  a  certain 
extent.  Reagents,  the  application  of  which  we  will  now  con- 
sider, are  necessary  for  the  further  penetration  into  their  struc- 
ture. 

Let  us  commence  with  the  last-mentioned  covering  of  epi- 
dermoid cells  (figs.  112  &,  ll^y).  The  action  of  concentrated 
sulphuric  acid  for  a  few  minutes,  the  importance  of  which  was 


EPITHELIUM,    NAILS,    HAIR. 


267 


indicated  many  years  ago  by  H.  Meyer,  is  an  excellent  means  of 
separating  the  cells.  The  same  result  may  be  accomplished  with 
alkalies,  though  much  more  slowly.  Moleschott  praises  a  potash 
solution  of  4.6  per  cent.  When  this  has  acted  for  about  forty 
hours  (in  the  cooler  temperature  of  winter)  the  cells  begin  to 
separate  from  the  shaft  of  the  hair.  After  three  or  four  days 
the  cells  are  everywhere  isolated  in  the  most  beautiful  manner. 
Solutions  of  soda  may  also  be  used. 


Fig.  118.  Cells  of  the  root-sheaths ; 
inner  root-sheath  with  Henle's  (a) 
and  Huxley's  (6)  layer;  c,  cells  of  the 
external  sheath. 


Fig.  114.  a,  cells  of  the  hair- 
bulb;  6,  from  the  commencement 
of  the  shaft ;  c  cortical  mass  treated 
with  sulphuric  acid,  and  at  d  sepa- 
rated into  plates ;  ef,  cells  of  the 
cuticle  of  the  hair. 


The  use  of  concentrated  sulphuric  acid  at  a  moderate  tem- 
perature is  the  best  means  of  demonstrating  the  cortical  layer 
of  the  shaft  of  the  hair,  and  for  isolating  its  peculiar  plate-like 
cells.  After  several  minutes  it  will  be  found  that  the  cuticle 
is  commencing  to  separate,  and  that  the  surface  of  the  shaft  has 
become  rough  and  felt-like.  After  a  short  interval,  especially 
when  the  hair  is  made  to  roll  with  a  little  pressure,  the  spindle- 
shaped  cells  begin  to  peel  off.  The  inner  layers  (b  d)  after- 
wards become  separated,  until,  finally,  the  medullary  substance 
is  exposed. 

These  plates  may  also  be  split  off  in  groups  by  mechanical 
means.  For  this  purpose,  a  dry  hair  is  to  be  placed  on  the 


268  SECTION   TWELFTH. 

slide  and  scraped  in  the  direction  from  the  point  towards  the 
root.  The  scrapings  are  to  be  moistened  and  placed  under  the 
microscope  (c). 

Alkalies  were  long  since  recommended  for  rendering  visible 
the  shrunken  air- vesicles  of  the  medulla  (Kolliker).  For  the 
medullary  cells  of  the  hairs  of  the  beard,  and  especially  blonde 
hairs,  Moleschott  praises  the  maceration,  for  one  or  two  days,  in 
a  3  per  cent,  solution  of  soda.  Placing  the  hair  for  several 
days  in  a  2  per  cent,  solution  of  potash,  or  a  longer  immersion 
in  one  of  4.6  per  cent,  produces  good  specimens. 

The  following  process  is  most  to  be  recommended  for  obtain- 
ing transverse  sections  through  the  hair-shaft:  A  bundle  of 
hairs  is  to  be  stuck  together  with  glue  or  gum-arabic  and  dried. 
The  sections,  obtained  by  the  aid  of  a  sharp  knife,  are  to  be 
softened  in  hot  or  cold  wrater.  Henle,  many  years  ago,  gave  an- 
other original  method,  A  short  time  after  shaving,  the  same 
operation  is  to  be  repeated,  and  the  sections  of  the  beard  fished 
out  of  the  lather.  Transverse  sections  may  also  be  made  from 
hairs  which  are  fixed  in  cork  or  gutta-percha  (Harting,  Reich- 
ert). 

The  employment  of  very  dilute  acetic  acid  is  very  useful  for 
examining  the  cells  of  the  outer  root-sheath.  Stronger  solutions 
of  potash  are  used  for  the  cells  of  the  inner  root-sheath. 

We  shall  afterwards  consider  a  few  of  the  pathological  condi- 
tions. 

The  first  rudiments  of  foetal  hairs  are  obtained  from  sections 
of  skin  hardened  in  chromic  acid  or  alcohol.  Tingeing  with 
carmine  is  very  useful.  The  later  stages  of  development  are 
studied  in  a  similar  manner. 

Hair  preparations  are  to  be  mounted  dry  in  Canada  balsam 
or  in  glycerine,  according  to  circumstances. 


0cction 


CONNECTIVE  TISSUE  AND  CARTILAGE. 

MODERN  histology  designates  at  present  with  the  name  of  con- 
nective substance  a  series  of  tissues  which  are  nearly  related, 
although  proving  different  enough  in  their  terminal  forms,  and 
which  are  all,  directly  or  indirectly,  interchangeable.  They 
also  take  their  origin  from  very  similar  textures,  and  thus  pre- 
sent substantial  evidence  of  being  members  in  a  natural  series 
of  relationship.  Gelatinous  tissue,  reticular  and  ordinary  con- 
nective tissue,  fat,  cartilage,  bone,  and  dentine  are  to  be  enu- 
merated here. 

These  members  also  resemble  each  other  in  still  another 
physiological  regard.  They  are  tissues  of  low  rank,  which  do 
not  take  part  in  the  higher  vital  processes,  but,  on  the  contrary, 
they  form  throughout  the  whole  body,  in  all  its  parts,  a  widely 
expanded  framework  (although  of  varying  quantity),  in  the  spaces 
of  which  are  embedded  other  tissues,  such  as  muscles,  nerves, 
vessels,  glandular  cells,  etc.  Yirchow  deserves  the  credit  of 
having,  by  a  series  of  investigations,  shown  the  importance  of 
connective  tissue  in  pathological  new  formations. 

1.  As  gelatinous  tissue,  we  distinguish  soft  transparent  masses, 
consisting  of  round  or  star-shaped  cells  (figs.  115,  116),  which 
have  between  them  a  consid- 
erable quantity  of  an  ordi- 
nary homogeneous,  slimy  in- 
tercellular substance.  Near- 
ly all  of  them  belong  to  the 
foetal  period  of  life,  and  con- 
cern either  transitory  organs  Fig.  115.  Tissue  of  the  ^^y  o£  a  hu. 
or  are  only  development 

stages  of  the  ordinary  connective  tissue.     A  single  one  of  these, 
of  a  peculiar  watery  form  with  stunted  cells,  persists  :  the  vit- 


270 


SECTION   THIRTEENTH. 


reous  body  of  the  eye  (fig.  115).  The  extreme  softness  of  all 
these  tissues  renders  it  very  difficult  to  obtain  tolerable  prepara- 
tions. At  the  most,  the  pale  and  deli- 
cate cells  may  be  studied  with  a  strongly 
shaded  field  without  further  treatment. 
Hardening  media  are  therefore  necessary, 
and  among  these  chromic  acid  and  bi- 
chromate of  potash  take  the  first  rank. 
As  a  rule,  a  chromic  acid  solution  of 
0.5-2  per  cent,  hardens  the  tissue  to 
such  an  extent  that  sections  may  be  made 
from  it  with  a  sharp  razor.  With  one 
of  the  organs  which  belongs  here,  the 
umbilical  cord,  the  drying  method  may 
be  very  suitably  employed.  Neumann 
has  given  a  peculiar  but  very  appropriate 
process  for  the  vitreous  humor.  It  is  to 
be  saturated  for  1-2  days  with  the  albu- 
men of  an  egg,  and  then  hardened  by  a 
momentary  immersion  in  hot  water,  after 
which  it  is  to  be  placed  in  alcohol.  In 
this  way  the  organ  is  not  only  rendered 
more  consistent,  but  also  darker. 

In  consequence  of  the  delicacy  and 
paleness  of  the  cells  of  gelatinous  tissue, 
tingeing  is  very  much  in  place.  Excellent  preparations  of  the 
vitreous  fluid  are  obtained  with  aniline  blue. 

Preparations  of  the  gelatinous  tissues  may  be  preserved,  after 
tingeing,  in  glycerine. 

2.  With  the  name  of  reticular  connective  tissue  we  designate 
a  reticulated  framework  made  up  of  star-shaped  cells,  which 
no  longer  harbors  in  its  sometimes  wider,  sometimes  extremely 
narrow  meshes  the  mucous  fluid  of  the  gelatinous  tissue  ;  on  the 
contrary,  its  contents  are  different.  They  consist  either  of 
lymph-corpuscles — in  which  case  the  tissue  has  recently  been 
called  "  adenoid  "  or  "  cytogenetic  "  (His,  Kolliker) — or  of  drops 
of  fat  (hibernating  glands),  or  of  nervous  elements  (spinal  cord, 
brain  and  retina).  Here,  as  in  the  whole  connective  substance 


116.  Cells  of  the  ena- 
mel organ  of  a  four  months' 
embryo ;  at  a  smaller,  at  b 
larger  and  more  developed 

star-shaped  cells. 


CONNECTIVE    TISSUE   AND    CARTILAGE.  271 

group,  we  cannot  speak  of  a  sharply  demarcated  tissue.  The 
reticulated  often  passes  over  into  ordinary  connective  tissue,  and 
probably  also  into  gelatinous  tissue. 

If  any  tissue  of  the  body  is  qualified  for  showing  the  great 
value  of  the  more  modern  methods  of  investigation,  it  is  just 
this  reticular  connective  tissue  (fig.  117),  which  for  many  years 
has  been  frequently  examined  and  formerly  caused  numerous 
controversies.  All  the  forms  in  which  our  tissue  occurs  in  the 
lymphatic  glands,  lymphoid  follicles  of  the  thymus,  spleen,  in- 
testinal mucous  membrane,  etc.,  are  too  soft  to  permit  of  an 
examination  being  made  without  previous  preparation.  It  is, 
therefore,  indispensable  to  employ  hardening  media  for  several 
days  beforehand.  Among  these,  chromic  acid,  bichromate  of 
potash,  and  alcohol  take  the  first  rank.  When  these  glandular 
organs  or  the  intestinal  mucous  membrane  have  attained  the 


Fig.  117.    Eeticulated  connective  tissue  from  a  Peyer's  follicle  of  an  old  rabbit,   a,  the  capillary 
vessels  ;  6,  the  reticulated  connective  tissue  framework ;  c,  lymph  corpuscles. 

proper  degree  of  hardening,  the  finest  possible  sections  are  to 
be  made  from  them  with  the  sharp  and  moistened  blade  of  a 
razor.  These  sections  are  to  be  carefully  brushed,  in  the  man- 


272  SECTION   THIRTEENTH. 

ner  indicated  by  His,  with  a  soft  camel's-hair  brush.  Tingeing 
with  carmine  and  subsequent  washing  in  slightly  acidulated 
water  serve  for  demonstrating  the  nuclei  at  the  nodular  points 
of  the  network.  They  will  then  be  readily  seen,  especially  in 
young  subjects.  However,  all  of  the  innumerable  nodular 
points  do  not  have  a  nucleus,  as  not  only  the  simple  processes  of 
the  cells,  but  also  the  ramifications  of  these  processes  become 
united  with  each  other,  so  that  the  cell  radii  present,  together 
with  the  nucleated  centres,  a  number  of  non-nucleated  nodular 
points.  Tingeing  with  carmine  will  also  prevent  one  from  mis- 
taking the  stained  nucleus  for  the  transverse  section  of  a  verti- 
cally ascending  colorless  reticulated  fibre.  In  older  animals — 
and  our  drawing  is  taken  from  such  a  one — the  nuclei  may, 
indeed,  be  entirely  wanting  in  a  few  places,  and  frequently  only 
such  as  are  stunted  and  shrivelled  can  be  recognized.  In  condi- 
tions of  irritation,  however,  they  soon  resume  their  former  dis- 
tended appearance.  A  larger  or  smaller  residue  of  the  lymph- 
corpuscles  (c)  will  be  perceived  in  the  meshes  of  the  tissue, 
according  as  the  brushing  is  continued  for  a  longer  or  shorter 
period. 

In  many  cases  it  is  not  easy  to  hit  upon  the  proper  degree  of 
hardening,  and  on  it,  in  reality,  everything  depends.  If  the 
preparation  is  over-hardened  it  does  not  permit  of  the  sufficient 
removal  of  the  lymph-cells;  if  not  hardened  to  a  sufficient 
degree,  the  whole  frequently  falls  to  pieces  after  a  few  strokes 
with  the  brush. 

For  the  intestinal  mucous  membrane  and  most  of  the 
lymphoid  organs  I  prefer  alcohol  to  chromic  acid.  The  pieces, 
which  should  not  be  too  large,  are  to  be  placed  in  a  consider- 
able quantity  of  fluid  for  the  first  two  days.  This  should  con- 
sist of  alcohol  of  about  36°,  which  is  to  be  diluted  with  an 
equal  part  of  water.  The  fluid  is  then  to  be  replaced  by  the 
same  alcohol,  but  without  the  former  addition  of  water ;  gene- 
rally, after  from  four  or  five  days  to  a  week  the  tissue  is  in  a 
proper  condition  for  brushing.  Well-hardened  pieces  may  in 
this  way  be  preserved  in  weak  alcohol  for  months  and  years. 
Yery  strong  alcohol  is  to  be  entirely  avoided. 

If  it  be  desired  to  use  chromic  acid,  commence  with  a  solu- 


CONNECTIVE    TISSUE    AND    CAKTILAGE.  273 

tion  of  about  2-5  per  thousand,  and  proceed  gradually,  chang- 
ing the  fluid  to  one  of  1  per  cent.  Chromate  of  potash  is  to  be 
used  in  a  corresponding  quantity  (concerning  which  p.  139  is 
to  be  compared). 

The  reticular  connective  tissue  of  the  lymphatic  glands, 
Fever's  follicles,  and  the  Malpighian  bodies  of  the  spleen,  may 
be  recognized  with  comparative  facility.  The  thymus  and  the 
tissue  of  the  pulp  of  the  spleen  give  more  trouble.  Its  recog- 
nition is  difficult  in  the  hibernating  glands,  which  I  have 
investigated  with  Hirzel,  and  to  a  still  higher  degree  in  the 
nervous  organs,  especially  in  the  gray  substance  of  the  spinal 
cord  and  the  brain,  likewise  the  retina  of  the  eye.  More  dilute 
solutions  of  chromic  acid  than  those  above  mentioned  (J— |-  gr. 
to  1  ounce)  are  to  be  used,  and  allowed  to  act  for  several  da^. 
Yery  strong  objectives  should  also  be  used.  We  shall  return 
to  this  subject  in  speaking  of  the  organs  in  question. 

Tinged  preparations,  mounted  in  dilute  glycerine,  afford  the 
best  specimens  for  a  collection. 

3.  The  examination  of  fat  tissue  is  simple  and  causes  no 
trouble,  whether  a  simple  form  of  the  same  (fig.  118)  is  con- 
cerned, or  a  pathological  new  formation, 
for  example  a  lipoma. 

A  small  piece  of  the  tissue  (a)  is  to  be 
picked  in  the  fluid  media  and  then  re- 
viewed with  a  low  power.  The  large, 
sometimes  smoother,  sometimes  rougher 
cells  will  be  recognized  pressed  closely 
together,  often  with  a  polyhedral  flatten- 
ing. At  the  same  time,  a  number  of  free 
globules  of  fat  (I)  will  be  met  with  in 
consequence  of  the  laceration  of  the  cells 
which  has  occurred.  The  optical  proper- 
ties  of  both  are  quite  similar.  We  per- 
ceive  a  pellucid,  sometimes  slightly  yel- 
lowish  tinged  substance,  having  sharp, 

dark  contours  with  transmitted  light,  but  with  incident  light  a 
silver-like  lustre  and  a  whitish  or  yellowish  periphery.     "While 
the  fat-cells  are  of  a  definite  size,  that  of  the  free  drops  of  fat 
18 


<  SECTION    THIRTEENTH. 

varies  exceedingly.     The  latter  flow  together  under  pressure, 
but  the  cells  do  not. 

In  order  to  demonstrate  the  cell  membrane,  it  is  necessary 
either  to  rupture  the  cell,  in  which  case  the  former  remains 
behind  as  a  collapsed  sac  (c)  after  the  fat  has  flowed  out,  or 
the  fat  is  to  be  removed  by  chemical  means  with  alcohol,  ether, 
or  benzine,  which  last  was  recently  recommended  by  Toldt  for 
this  purpose.  The  nucleus  may  be  demonstrated  by  tingeing  it 
with  carmine  in  the  ordinary  way. 

The  treatment  with  picric  acid  and  carmine,  and  the  subse- 
quent addition  of  formate  of  gly- 
cerine affords  very  handsome  speci- 
mens (Flemming). 

Not  unfrequently,  a  deposition 
occurs  within  the  fat-cells  of  crys- 
talline needle-shaped  masses  (tig. 
119,  c\  the  same  as  we  have  already 
met  with  in  acid  pus.  A  prolonged 
immersion  in  glycerine  almost  in- 
variably produces  such  a  crystalli- 
ng, iin.  Human  fat-cells  containing  Cation  within  the  Cell  Cavity. 

In  order  to  stll(ty the  blood-vessels 
**  ordinary  of  fat  tissue,  injections  are  to  be 
made  with  transparent  masses,  car- 
mine, or  Prussian  blue,  and  in  making  the  microscopic  examin- 
ation pure  glycerine  is  to  be  used  as  a  medium,  wThich  last,  in 
consequence  of  its  strong  refracting  power,  is  very  well  adapted 
for  fat-cells  in  general. 

Glycerine  (pure  or  mixed  with  formic  acid,  p.  211)  is  to  be 
used  for  mounting,  or,  if  the  fat  tissue  is  injected,  Canada  bal- 
sam may  be  advantageously  employed.  The  previously-men- 
tioned solution  of  arsenious  acid  (p.  215)  has  been  recommended 
by  Harting. 

4.  Ordinary  connective  tissue  is  very  widely  diffused  and  con- 
sists, in  its  developed  form,  of  a  fibrous  substance  which  is  divi- 
sible into  bundles  and  fibrillse,  and  in  which  long  or  stellate 
cells,  the  frequently-mentioned  connective-tissue  corpuscles,  are 
met  with,  as  are  also  the  various  phases  of  elastic  tissue.  The 


CONNECTIVE    TISSUE    AND    CARTILAGE.  275 

whole  lies  embedded  in  an  extremely  variable  quantity  of  homo- 
geneous basis  substance. 

If  living  connective  tissue  be  selected  from  a  suitable  place, 
for  instance,  in  the  frog,  the  thin  transparent  membrane  (to 
which  Kuhne  called  attention)  between  the  crural  muscles  (fig. 
120),  and  examined  with  the  addition  of  lymph,  one  may  recog- 

I 


Fig.  120.  A  piece  of  living  connective  tissue  from  the  tipper  part  of  the  thigh  of  a  frog  (the 
cells  are  represented  somewhat  more  pressed  together  than  they  usually  lie),  a,  contracted  cell ; 
&,  radiated,  expanded  connective-tissue  corpuscles,  one  of  them  without  a  visible  nucleus ;  c,  one 
with  a  vesicular  nucleus ;  d  and  e,  immovable  cells ;  /,  fibrillae ;  fir,  simple  bundle  of  connective 
tissue ;  A,  plexus  of  elastic  fibres. 

nize  in  the  pellucid  basis-substance  the  fibrillse  (f)  and  bundles 
of  the  connective-tissue  fibres  (<?),  and  also  a  network  of  very 
fine  elastic  fibres  (7i).  The  connective-tissue  corpuscles  then 
appear  as  flat,  membraneless  cells,  consisting  of  a  nucleus  and 
fine  granular  protoplasma.  Several  varieties  of  these  cells  may 
be  noticed  (a  and  J,  <?,  d  and  0),  and  one  may  at  the  same  time 
convince  one's  self  that  the  first  two  varieties  of  the  connective- 
tissue  corpuscles  (a  ft  c)  have  a  sluggish,  but  unmistakable  vital 
contractility,  so  that  the  cell  a  gradually  changes  to  such  forms 
as  are  represented  in  our  figure  at  b.  However,  as  we  now 
know,  the  shape  is  even  yet  not  completely  described.  An  un- 
commonly pale  peripheral  portion,  which  may  be  readily  over- 
looked, gives  the  whole  thing,  after  its  death,  the  appearance  of 
an  oblong,  iiidentated  lamella,  which  is  bent  over  and  folded  in 


276  SECTION    THIRTEENTH. 

various  ways.  This  appearance  of  the  connective-tissue  cell 
(noticed  many  years  ago  in  tendons)  is  also  maintained  in  the 
solidified  connective  tissue  of  the  higher  animals  (Eanvier, 
Schweigger-Seidel,  and  Flemming).  Together  with  these,  the  re- 
markable amoeboid  migratory  cells,  the  emigrated  lymph-cor- 
puscles, which  we  mentioned  at  page  245,  are  met  with.  Ac- 
cordingly, the  fixed  have  been  distinguished  from  the  migratory 
cells  of  the  connective  tissue. 

As  the  proportion  of  the  cells,  fibrillse,  and  elastic  elements 
varies  considerably,  the  form  of  the  tissue  is  necessarily  modi- 
fied in  accordance  with  these  several  admixtures.  The  diversity 
which  the  twisting  and  interweaving  of  its  bundles  present  is 
not  less  considerable. 

If  a  piece  of  dead  connective  tissue  be  prepared  in  a  fluid 
medium  with  the  aid  of  sharp  needles,  it  may  be  very  readily 


Pig.  121.  Connective-tissue  bundles  (at  the  left,  several  isolated  fibrillae)  with  very  abundant 
homogeneous  interstitial  substance. 

separated  into  the  above-mentioned  strings  or  bundles  (fig.  121). 
The  bundles  themselves  show  a  striation  running  parallel  with 
their  long  axes,  and  may  be  separated,  in  accordance  with  the 
latter,  into  finer  strings,  and,  finally,  into  extremely  thin,  homo- 
geneous, more  or  less  undulating  fibres  or  threads,  the  so-called 
primitive  fibrillse. 

While  in  former  times  the  anatomists  adopted  a  fibrillated 


CONNECTIVE    TISSUE    AND    CAETILAGE.  277 

condition  of  the  connective  tissue  as  a  simple  expression  of  this 
very  easily  made  observation,  Reichert,  in  the  middle  of  the  fifth 
decade  of  this  century,  pronounced  these  fibres  to  be  artificial 
products,  and  the  longitudinal  striations  to  be  the  optical  ex- 
pression of  the  folding  and  wrinkling  of  a  thoroughly  homoge- 
neous membrane. 

Controversies  were  waged  for  a  long  time  concerning  the 
latter  acceptation.  It  was  only  at  a  later  period,  when  the 
method  of  isolation  by  chemical  means  had  been  discovered, 
that  the  preexistence  of  these  fibrillse  (which  the  reader  already 
recognizes  from  fig.  120),  could  be  proved  in  the  most  indubi- 
table manner.  If  the  connective  tissue  be  treated  alternately 
with  reagents  which  cause  it  to  swell  and  to  shrink,  the  finest 
fibres  appear  in  the  most  beautiful  manner  (Henle).  Further 
observations  were  then  made  by  Rollett. 

If  a  portion  of  human  tendon  be  immersed  for  a  week  or 
more  in  lime-water,  and  then  a  bundle  of  it  placed  on  the  slide, 
one  may  readily  succeed,  by  inserting  the  preparing  needles 
into  the  middle  of  the  same,  in  drawing  it  out  into  longitudinal 
fibres  of  greater  or  lesser  calibre,  which  cross  each  other  at 
acute  angles.  All  attempts  at  spreading  out  the  tissue  as  a 
homogeneous  membrane  in  accordance  with  Reichert's  views 
are  unsuccessful,  and  cause  it  to  split  up  into  fibrillse.  Baryta- 
water  produces  the  same  effect,  but  in  a  much  shorter  time-^- 
f  rom  4  to  6  hours. 

For  the  microscopical  investigation  it  is  necessary  to  remove 
the  hydrate  of  lime  or  baryta,  either  by  washing  for  a  long  time 
in  water,  or  by  the  addition  of  so  much  acetic  acid  as  just  suf- 
fices to  neutralize  the  lime  or  baryta.  The  lime  or  baryta  water 
dissolves  an  albuminoid  body,  which  is  evidently  the  cement 
substance  of  the  fibrillse. 

Although  one  series  of  connective-tissue  textures  behave 
similarly  in  this  regard,  others  present  a  deviation.  The  co- 
rium  may  serve  as  an  example.  This  is  separated  by  the  same 
treatment  into  stronger,  apparently  entirely  homogeneous  fibres 
which  can  only  be  split  up  into  the  longitudinally  arranged 
fibrillge  after  a  long-continued  maceration  (from  10-12  days)  in 
lime-water. 


278  SECTION   THIRTEENTH. 

According  to  Rollett's  observations,  the  fasciculi  of  the  sclero- 
tica,  the  apoiieuroses,  the  fibrous  capsular  ligaments,  the  dura 
mater,  and  the  interosseous  ligaments,  are  formed  after  the 
type  of  the  tendons. 

The  examination  of  connective  tissue  by  polarized  light  also 
speaks  for  the  presence  of  the  fibrillse.  They  are  positively 
double  refracting,  and  the  optical  axis  lies  in  the  longitudinal 
direction  of  the  fibrillse.  None  of  the  reagents  which  maintain 
the  fibrous  appearance  of  the  connective  tissue  alter  the  optical 
nature  of  the  same  to  any  considerable  extent.  On  the  con- 
trary, methods  of  treatment  which  render  the  connective  tissue 
apparently  homogeneous,  also  change  the  double  refraction  very 
much  (W.  Muller). 

The  same  arrangement  as  in  the  external  skin  is  found  in  the 
conjunctiva,  the  subcutaneous  cellular  tissue,  the  submucous  tis- 
sue of  the  intestinal  canal,  and  the  tunica  adventitia  of  the  vessels. 

The  interweaving  of  the  connective-tissue  bundles,  and  the 
entire  arrangement  of  a  connective-tissue  part,  may  be  recog- 
nized in  dried  preparations  by  making  coarse  sections  from 
them  and  simply  softening  these  in  water.  Tingeing  with  car- 
mine may  also  be  suitably  employed. 

A  finely  punctated  substance  may  be  discovered  in  the  trans- 
verse sections  of  the  fasciculi,  which  many  microscopists  have 
declared  to  be  the  transverse  sections  of  the  connective  -tissue 
fibrillse,  as,  for  example,  in  the  tendons. 

In  order  to  demonstrate  the  cellular  and  elastic  elements 
which  occur  between  the  fibrillae,  reagents  have  been  used  for 
many  years  which  cause  the  fibrillse  to  swell,  and  at  the  same 
time  lower  their  refractive  power  to  such  an  extent  that  it  be- 
comes equal  to  that  of  the  water  which  is  added.  Thus  is 
caused  an  apparent  dissolution  of  the  fibrillae,  and  the  remain- 
ing elements  of  the  connective  tissue  are  rendered  prominent, 
although  the  cells  have  undergone  extensive  modifications  and 
disfigurations. 

This  manner  of  action  has  been  longest  known  in  connection 
with  acetic  acid,  but  other  organic  acids  may  also  be  employed. 
Pyro-acetic  acid  has  been  frequently  used  for  this  purpose, 
sometimes  undiluted,  sometimes  diluted  with  an  equal  volume 


CONNECTIVE    TISSUE    AND    CARTILAGE. 


279 


of  water.  Mineral  acids,  such  as  nitric  and  muriatic  acids,  in  a 
condition  of  extreme  dilution,  exert  a  similar  effect.  The  latter, 
of  0.1  per  cent.,  behaves  the  same  as  acetic  acid. 

It  is  only  necessary  to  neutralize  the  acid  with  ammonia  to 
cause  the  fibrillae  to  reappear. 

The  connective  tissue  fibres  also  undergo  the  same  swelling 
in  alkalies  as  in  these  acids.  As  was  the  case  with  epithelium, 
the  supplementary  addition  of  water  produces  a  rapid  dissolu- 
tion of  the  fibres. 

In  still  another,  much  more  conservative  manner,  namely,  by 
employing  a  fluid  medium  of  strong  refractive  power,  the  em- 
bedded structures  may  be  recognized  in  the  unswollen  connect- 
ive tissue.  Glycerine  is  of  the  highest  value  in  this  regard. 

The  swelling  of  the  connective-tissue  from  the 
above-mentioned  action  of  acids  may  give  rise  to 
peculiar  appearances.  In  many  portions  of  the 
body  the  connective-tissue  bundles  are  invested 
like  a  sheath  by  a  condensed  substance.  Now 
this  expands  to  a  much  slighter  degree,  and  con- 
sequently it  is  not  unfrequently  torn  across  and 
then  more  and  more  pressed  together  by  the  con- 
tained mass,  which  protrudes  with  a  certain  force, 
until  finally,  in  consequence  of  the  strong  com- 
pression, it  has  assumed  the  form  of  a  ring.  This 
ring  is  very  similar  in  appearance  to  that  of  an 
elastic  fibre  running  in  a  circular  direction,  for 
which  it  has  also  frequently  been  mistaken. 

But  enough  about  the  fibrillge.  Let  us  inquire 
into  the  methods  of  examining  the  cells. 

A  thin  strip  of  interstitial  connective  tissue 
may  be  cut  from  the  living  body  and,  after  being 
moistened  with  lymph  and  enclosed  in  the  moist 
chamber,  examined.  The  appearances  presented 
are  instructive ;  but  the  wrinkling  of  such  a 
lamella  is  a  fatal  circumstance,  as  every  observer 
has  experienced. 

We  are  therefore  indebted  to  Ranvier,  a  French  histologist, 
for  the  discovery  of  a  new  method.  Artificial  oedema  is  to  be 


Fig.  122.  A 
connective-tissue 
bundle  from  the 
base  of  the  human 
brain,  treated  with 
acetic  acid. 


280  SECTION   THIRTEENTH. 

produced  by  injecting  the  tissue.  Iodine  serum  or  a  weak 
solution  of  the  chromate  of  potash,  for  instance,  may  be  in- 
jected into  the  subcutaneous  or  intermuscular  connective  tissue 
of  a  frog.  A  beautiful  preparation  may  be  obtained  by  rapidly 
placing  a  fine  section  of  this  gelatinous  infiltrated  mass  on  the 
slide  under  the  covering-glass.  A  weak  solution  of  nitrate  of 
silver  (0.1  per  cent.)  is  in  a  still  higher  degree  qualified  as  an 
injecting  fluid,  as  by  this  means  the  pale  borders  of  the  connec- 
tive-tissue cells  are  covered  with  a  granular  precipitate  and  thus 
rendered  more  distinct.  Masses  which  become  hardened,  such 
as  solutions  of  gelatine,  are  much  preferable.  Flemming, 
imitating  Ranvier's  process,  made  use  of  glycerine-gelatine 
(p.  211),  to  which  half  its  volume  of  the  above-mentioned  solution 
of  nitrate  of  silver  was  added.  The  infiltrated  mass  was  then 
cut  out  and  exposed  to  a  freezing  temperature.  Thin  sections 
were  then  made  and  washed  out,  then  colored  for  6-12  hours 
in  picric  acid,  and,  after  being  again  washed  out  in  water, 
mounted  in  glycerine  (plain  or  containing  formic  acid). 

Formerly,  the  cellular  elements  were  isolated  by  dissolving 
the  intercellular  substance.  This  readily  succeeds,  as  the  latter 
becomes  changed  into  gelatine. 

As  is  well  known,  connective  tissue  may  be  converted  into 
gelatine  by  treating  it  for  a  variable  length  of  time  with  boiling 
water.  This  may  in  part  stand  in  connection  with  structural 
conditions,  as  soft  connective  tissue  usually  dissolves  more  rapid- 
ly than  that  which  is  more  firmly  united. 

This  action  is,  however,  altogether  too  energetic  for  histologi- 
cal  purposes.  The  softer  connective  tissue,  at  least,  may  be 
dissolved  by  other  means  in  a  much  more  conservative  manner. 
After  softening  it  for  about  a  day  in  very  slightly  acidulated 
water,  it  may  be  dissolved  in  24  hours  by  moderately  warming 
the  water  to  35-40°  C.  At  the  muscular  tissue  we  shall  again 
have  to  speak  of  this  procedure,  which  deserves  a  more  extend- 
ed application. 

It  would  lead  us  too  far  to  describe  these  artificially  changed 
connective-tissue  cells  in  this  place.  For  the  rest  we  refer  to 
the  two  adjoining  figures,  123  and  124,  which  were  drawn  from 
alcoholic  preparations. 


CONNECTIVE    TISSUE    AND    CARTILAGE. 


281 


Cohnheim  has  very  properly  recommended  the  impregnation 
of  connective  tissue  with  gold. 


Fig.  123.  Spindle  cell,  from  the 
tendon  of  a  hog's  embryo  eight 
inches  long,  a,  cell  with  proto- 
plasma;  &,  connective-tissue  fi- 
brillje. 


Fig.  124.  Soft  connective  tissue  from 
the  vicinity  of  the  tendo  Achillas  of  a 
human  embryo  of  2  months,  a,  spindle 
cells ;  6,  a  very  elongated  one  ;  c,  inter- 
cellular substance  with  fibrillae. 


Fig.  125.    Various  forms  of  human  elastic  fibres,   a,  unbranched,  6  and  c,  ramified. 

The  great  majority  of  the  so-called  elastic  fibres  (fig.  125)  are 
undoubtedly  of  a  solid  nature,  and  all  attempts  to  stain  them 


282  SECTION   THIRTEENTH. 

with  carmine  fail.  The  great  power  of  resistance  which  they 
present  renders  their  examination  comparatively  easy  and 
simple. 

Parts  which  are  very  rich  in  elastic  tissue  require  a  somewhat 
more  careful  preparation.  In  this  way  the  great  extensibility 
of  the  finest  fibres  (a)  will  be  noticed  ;  at  the  same  time  it  will 
be  seen  that  these  fibres  may  assume  the  strangest  convolutions 
in  the  swollen  connective  tissue.  Thicker  elastic  filaments 
prove  to  be  much  less  extensible,  and  frequently  present  them- 
selves as  fragments  (c). 

The  fasciculi  of  a  tendon  of  the  external  skin  or  of  the  sub- 
cutaneous cellular  tissue  may  be  employed  for  the  first  exami- 
nation of  connective  tissue.  Do  not  spare  the  trouble  of  un- 
ravelling a  very  small  piece  in  water  or  an  indifferent  fluid.  For 
demonstrating  the  connective-tissue  corpuscles,  it  is  customary 
to  use  reagents  which  cause  the  tissue  to  swell,  especially  acetic 
acid.  Tingeing  with  carmine  is  also  useful.  Ranvier  has  also 
made  us  acquainted  with  a  useful  method  of  examining  tendin- 
ous tissues. 

The  extremely  thin  fibres  from  the  tails  of  small  mammalia, 
such  as  young  rats,  mice,  and  moles  are  used.  If  the  last 
caudal  vertebrae  be  torn  from  their  attachments,  a  considerable 
length  of  the  tendons  remains  connected  with  the  separated 
parts.  Their  ends  are  to  be  fastened  to  the  slide  with  sealing- 
wax,  carmine  is  then  to  be  employed,  together  with  the  usual 
supplementary  treatment  with  acetic  acid;  glycerine  contain- 
ing formic  acid  is  finally  added. 

Elastic  fibres  become  prominent  after  treatment  with  acids 
and  alkalies.  An  opportunity  of  studying  them  is  presented  in 
the  subcutaneous  cellular  tissue,  the  corium,  and  the  ligamen- 
tum  nuchse  of  the  mammalia.  A  more  suitable  object  for  learn- 
ing the  great  diversity  in  the  manner  of  appearance  of  elastic 
tissue  can  scarcely  be  found  than  the  wall  of  a  large  artery 
from  one  of  the  larger  mammalia,  the  various  layers  of  which 
are  to  be  separated  with  forceps  and  scalpel. 

Embryonic  connective  tissue  (and  many  of  the  pathological 
new  formations  of  our  tissue,  at  a  similar  stage  of  organization 
and  consistence,  are  to  be  enumerated  here)  is  to  be  examined 


CONNECTIVE    TISSUE    AND    CARTILAGE. 


283 


B 


partly  fresh  in  indifferent  fluids,  partly  after  the  production 
of  an  oedema,  and  finally,  although  not  so  good,  in  prepara- 
tions hardened  by  chromic  acid  or  chromate  of  potash.     In 
order  to  decide  what  is  here  present  as 
elastic  tissue  (fig.  126),  the  use  of  alkalies, 
preferably  boiling  for  a  short  time  in  a 
10-15  per  cent,  solution  of  potash,  should 
not  be  neglected,  as  the  connective  tissue 
corpuscles  (A  a)  are  in  this  way  made  to 
disappear,  but  not  the  elastic  fibres  (B  c). 
Both  elements  react  alike  with  acetic  acid 

At  the  commencement  of  this  section 
we  alluded  to  the  importance,  which  is 
indeed  very  great,  of  connective  tissue  in 
pathological  formative  processes.  We  are 
prevented  by  the  narrow  limits  of  our  little 
book  from  making  more  than  a  few  re- 
marks on  this  subject,  which  is  now  being 
so  completely  revolutionized. 

Although,  until  within  a  few  years,  it 
was  generally  considered  that  pathological 
growths  consisting  of  lymphoid  cells  were 
formed  by  the  division  of  the  normal  con- 
nective-tissue cells,  the  emigration  of  the 
former  elements  from  the  blood  passages 
has  become  prominent,  in  consequence 
of  the  Weller-Cohnheim  theory.  It  is  certain  that  this  plays 
an  important  though  not  exclusive  role,  as,  according  to  Striek- 
er's experience,  a  complete  absence  of  participation  cannot  be 
ascribed  to  the  neighboring  connective-tissue  corpuscles.  At  all 
events,  in  such  difficult  matters  one  should  avoid  springing 
with  inconsiderate  haste  from  one  extreme  to  the  other. 

Such  collections  of  cells  may  again  disappear,  the  mass  melt- 
ing down  and  becoming  "  pus,"  in  the  old  sense  of  the  word. 
They  may  also  become  organized,  that  is,  form  new  connective 
tissue  accompanied  by  the  growth  of  vessels  in  them,  whereby 
the  migratory  cells  are  .transformed  into  connective-tissue  cor- 
puscles and  an  interstitial  substance  which  is  split  up  into 


Fig.  126.  From  the  liga 
mentum  nuchse  of  a  hog's 
embryo,  8  inches  long.  A 
side  view;  a,  spindle  cells  in  a 
fibrous  basis  substance  6  (al- 
cohol preparation) ;  B^  the 
elastic  fibres  brought  out  by 
boiling  in  a  solution  of  potash. 


284  SECTION   THIRTEENTH. 

bands  and  fibres.  Parts  which  have  been  divided  are  reunited 
in  this  manner,  and  then  one  speaks  of  cicatricial  tissue.  Loss 
of  substance,  occasioned  by  suppuration  or  ulcerative  destruc- 
tion, undergoes  essentially  the  same  restorative  process.  Luxu- 
rious growths  of  this  unripe  tissue,  which  is  overloaded  with 
lymphoid  cells,  constitute  the  so-called  granulations. 

Hypertrophic  connective-tissue  formations  are  frequently 
found  as  a  result  of  a  continued  distention  of  a  part  with  blood, 
the  so-called  congestive  and  inflammatory  processes,  but  like- 
wise without  any  cause,  spontaneous,  as  it  is  said.  Thickening 
of  the  various  integuments,  the  corium,  the  fibrous  and  serous 
membranes,  etc.,  are  to  be  enumerated  here  ;  likewise  intersti- 
tial growths  between  muscles,  nerves,  glands,  etc.  In  these 
cases  the  microscopic  examination  shows  an  increase  in  the 
iiumber  of  the  cells  and  of  the  intercellular  substance. 

The  various  tumors  consist  either  entirely  of  connective  tissue, 
or,  together  with  other  elements,  have  at  least  a  connective-tissue 
framework.  The  forms  in  which  they  appear  differ  extremely. 
In  many  we  meet  with  an  entirely  undeveloped  structure,  re- 
sembling granulation  tissue  or  that  of  lymphatic  glands,  as,  for 
instance,  in  syphilitic  tumors  and  in  tubercle.  Others,  the 
polymorphous  group  of  the  sarcomata,  constitute  a  transition  to 
a  more  highly  organized  variety  of  our  tissue.  The  latter  be- 
long, for  the  most  part,  to  the  fibroid  or  cellular  tissue  tumors. 
The  lipomata  are  formed  of  connective  tissue  with  collections 
of  fat-cells,  a  pathological  fat  tissue.  New  formations  of  gela- 
tinous tissue  also  occur  under  various  circumstances  and  con- 
stitute the  myxomata. 

The  carcinomata  or  cancerous  tumors,  those  enigmatical  and 
most  dangerous  new  formations  of  the  body,  are  embedded,  at 
least  in  the  normal  connective-tissue  textures,  and  show,  in  con- 
formity therewith,  a  framework  consisting  of  a  connective-tis- 
sue intercellular  substance.  In  the  sometimes  larger,  sometimes 
smaller  spaces  of  this  framework  lie  embedded  cells  which 
may,  in  certain  cases,  resemble  those  of  pavement  epithelium, 
but  generally,  however,  they  present  a  character  which  does  not 
thoroughly  correspond  to  that  of  any  .of  the  normal  cells,  al- 
though they  may  have  taken  their  origin  from  glandular  or 


CONNECTIVE    TISSUE    AND    CARTILAGE.  2 8 5 

epithelial  cells.  These  "  cancer  cells  "  are  capable  of  an  unlim- 
ited, exuberant  multiplication.  It  is  customary  to  distinguish 
between  certain  forms  of  carcinoma.  A  tumor  is  generally 
called  scirrhus  (Faserkrebs)  when  there  are  only  small  collections 
of  cells  embedded  in  a  firmly  interwoven  connective-tissue 
framework,  so  that  the  tumor  possesses  throughout  the  charac- 
ter of  hardness  and  firmness.  Inversely,  one  speaks  of  medul- 
lary carcinoma  where  large  aggregations  of  cells  occur  in  spaces 
of  considerable  size,  the  whole  having  a  softer  consistence,  and 
the  groups  of  cells  forming  masses  of  a  butter-and-cream-like 
nature.  If  the  cells  have  the  appearance  (but  not  the  group- 
like  arrangement)  of  pavement  epithelial  cells,  we  have  one 
form  of  epithelial  cancer,  while  the  others  have  cylindrical 
cells,  in  both  cases  certainly  descendants  from  the  epithelial 
and  glandular  cells.  If  the  substance  of  the  framework  pre- 
sents a  strongly  marked  fungous  (alveolar)  structure,  and  in  the 
numerous  spaces  lie  cells  which  are  undergoing  the  colloid 
transformation,  we  have  the  alveolar  or  colloid  cancer  of  the 
pathological  anatomists.  It  is  well  known  that  sharp  bounda- 
ries between  these  various  forms  of  carcinoma  do  not  exist,  that 
they  frequently  pass  into  each  other,  and  that  in  one  and  the 
same  tumor  some  localities  may  be  more  of  one  character, 
and  others  more  of  another. 

Finally,  let  us  inquire  into  the  method  of  examining  these 
abnormal  connective-tissue  structures.  They  are  substantially 
the  same  as  those  which  we  have  mentioned  for  the  normal 
tissues.  Sometimes  one  procedure,  sometimes  another  will  be 
necessary,  according  to  the  exceedingly  variable  consistence. 
In  a  fresh  condition,  and  by  the  employment  of  truly  indifferent 
media,  we  may  obtain  satisfactory  views  of  the  cells  and  their 
transformations  by  picking,  by  scraping  the  cut  surfaces, 
etc.  Hardening  methods  (chromic  acid,  chromate  of  potash, 
and  alcohol)  are  generally  resorted  to  in  order  to  ascertain  the 
further  arrangement.  It  is  very  well  to  place  small  pieces  of 
such  tumors,  and  if  possible  while  still  warm,  in  a  considerable 
quantity  of  absolute  alcohol.  One  may  then  proceed,  even  after 
a  few  hours,  to  the  preparation  of  thin  sections  (Waldeyer). 
Even  here,  tingeing  with  carmine  shows  many  things  very  hand- 


286  SECTION   THIRTEENTH. 

somely  ;  brushing  leads  to  the  isolation  of  the  framework  sub- 
stances. Fine  sections  also  constitute  the  most  important  means 
of  ascertaining  the  relations  of  the  so  important  region  of  de- 
marcation between  the  normal  and  diseased  connective  tissue. 

It  will  be  necessary  to  mount  most  preparations  of  connective 
tissue  in  fluid,  if  they  are  to  be  kept  as  permanent  specimens. 
The  first  of  Pacini's  fluids  (p.  213),  also  a  solution  of  sublimate 
(1),  salt  (2),  and  water  (100)  may  be  employed.  Another  mix- 
ture, consisting  of  sublimate  (1),  acetic  acid  (3),  and  water  (300) 
is  also  well  adapted  for  preserving,  although  the  action  of  the 
acid  makes  itself  felt.  Glycerine  media  will  be  resorted  to,  as 
a  rule.  If  an  untinged  preparation  is  to  be  mounted,  the  gly- 
cerine is  to  be  diluted  with  a  larger  quantity  of  water,  so  that 
the  former  may  not  become  too  transparent.  Stained  speci- 
mens permit  of  the  use  of  a  more  concentrated  glycerine.  The 
latter  preparations,  for  example  a  cornea,  the  section  of  a  ten- 
don or  of  a  scirrhus,  deprived  of  their  water  by  means  of  abso- 
lute alcohol,  not  unfrequently  present  a  very  fine  appearance 
when  mounted  in  Canada  balsam. 

5.  The  examination  of  the  tissue  of  cartilage  is  very  simple, 
as  it  has  a  degree  of  consistence  which  permits  of  thin  sections 
being  made  without  any  further  preparation.  Cartilage  which 
has  been  hardened  in  alcohol  and  chromic  acid  also  affords  very 
characteristic  and  good  specimens. 

Notwithstanding  its  consistence,  cartilage  is  a  tissue  which 
requires  foresight  in  the  employment  of  fluid  media  if  one  de- 
sires to  have  a  view  of  the  unaltered  texture.  Even  ordinary 
water  has  a  strongly  alterative  action  on  the  cartilage  cells, 
especially  those  of  young  animals. 

There  are  three  varieties  of  cartilage  to  be  distinguished : 
the  hyaline,  with  a  homogeneous  interstitial  substance  (fig.  127)  ; 
the  fibrous  or  reticular,  with  a  basis  substance  which  is  split  up 
into  bands  (fig.  128) ;  and,  finally,  the  connective-tissue  carti- 
lage (fig.  129),  in  which  a  few  cartilage  cells  are  found  between 
the  bundles  of  connective  tissue. 

For  the  first  examination  a  foetal  cartilage  may  be  used,  the 
fine  sections  from  which,  in  consequence  of  their  transparency, 
require  a  certain  shading  of  the  field.  A  bone  which  is  com- 


CONNECTIVE    TISSUE    AND    CARTILAGE.  287 


Pig.  127.  Hyaline  cartilage.  Fig.  128.  Kcticular  cartilage.  Pig.  129.  Connective-tis- 

sue  cartilage. 


Fig.  130.  Costal  cartilage  of  an  old  man.  a,  homogeneous ;  &,  split  up  into  bands ;  «,  flbrons 
Interstitial  substance ;  d,  e,  large  mother-cells ;  /,  a  mother-cell  with  considerably  thickened  cap- 
sule. 


288  SECTION   THIRTEENTH. 

mencing  to  ossify  may  be  used  for  studying  the  formation  of 
the  daughter-cells.  These  cell  formations  may  be  met  with,  of 
an  elegant  appearance,  close  to  the  calcified  tissue.  The  arti- 
cular cartilages  of  adults  form  very  suitable  objects,  and  the 
costal  cartilages  of  older  men  (fig.  130)  are  especially  useful  for 
investigating  the  textural  changes  which  occur  in  cartilage 
which  is  undergoing  senile  degeneration.  Together  with  ordi- 
nary semi-transparent  places  (a)  in  the  section,  others  will  be 
discovered  which  appear  more  opaque  with  transmitted  light, 
and  with  incident  light  they  have  a  peculiar  asbestos-like  lustre. 
The  transformation  of  the  interstitial  substance  into  a  system  of 
delicate  fibres  (c)  running  in  a  parallel  and  straight  direction 
may  also  be  seen  ;  one  may  also  meet  with  large,  often  colossal 
mother-cells  (d  e),  with  whole  generations  of  daughter-cells,  to 
which  Bonders  called  attention  many  years  ago.  Such  a  costal 
cartilage  affords  an  excellent  opportunity  for  studying  the  vari- 
ous stages  of  thickening  of  the  capsules  of  the  cartilage  cells 


Calcified  cartilage  tissue  requires  various  methods  of  treat- 
ment, according  to  the  quantity  of  calcareous  molecules  embed- 
ded in  it.  If  the  latter  be  but  scanty,  an  ordinary  watery 
medium  suffices.  If  the  calcification  be  more  extensive,  glycer- 
ine or  Beale's  mixture  of  alcohol  and  soda  is  to  be  used,  in  con- 
sequence of  its  stronger  refractive  power.  A  stage  of  calcifi- 
cation soon  arrives,  however,  in  which  even  these  reagents  are 
no  longer  capable  of  rendering  the  opaque,  dark  preparations 
transparent.  In  this  case  a  method  practised  by  H.  Miiller  is 
to  be  especially  recommended.  The  cartilage  is  to  be  immersed 
for  a  considerable  time  in  a  strong  chromic  acid  (1-2  per  cent.), 
the  action  of  which  may  be  assisted  by  the  addition  of  a  few 
drops  of  muriatic  acid.  After  the  solution  of  the  lime  mole- 
cules, the  preparation  is  rendered  very  intelligible  by  the  addi- 
tion of  glycerine.  We  shall  soon  see,  when  speaking  of  the 
process  of  ossification,  how  important  this  very  method  is  for 
the  recognition  of  extremely  difficult  relations. 

The  epiglottis  or  the  cartilage  of  the  ear  is  to  be  selected  for 
the  first  examination  of  reticulated  cartilage.  In  consequence 
of  the  opacity  of  the  basis  substance  the  section  cannot  be  made 


CONNECTIVE    TISSUE    AND    CAKTILAGE.  289 

too  thin.  At  the  borders  of  such  a  preparation  one  not  unfre- 
quently  meets  with  a  few  of  the  cartilage  cells  projecting  more 
or  less  above  the  interstitial  substance.  Glycerine  again  con- 
stitutes a  very  suitable  medium. 

The  examination  of  connective-tissue  cartilage  requires  the 
same  methods  as  connective  tissue.  The  cartilages  of  the  eye- 
lids are  to  be  recommended  for  the  first  examination. 

The  intervertebral  ligaments  are  to  be  selected  for  demon- 
strating the  varieties  of  cartilage  in  a  small  space  near  each 
other. 

The  polarizing  microscope  teaches  us  that  cartilage  likewise 
belongs  to  the  double  refracting  tissues.  We  are  not  as  yet 
sufficiently  enlightened  with  regard  to  the  direction  of  the  op- 
tical axis. 

Recently,  by  means  of  energetic  reagents,  the  apparently 
homogeneous  substance  of  hyaline  cartilage  has  been  completely 
reduced  to  a  system  of  thick  rings  or  area?  surrounding  the  in- 
dividual cells  or  groups  of  cells  ;  and  in  this  manner  the  origin 
of  these  basis  substances  from  the  cellular  elements  has  been 
proved  beyond  all  doubt  (Heidenhain,  Broder). 

In  order  to  obtain  this  important  appearance  (fig.  131),  the 
cartilage  may  be  digested  in  water,  at  a  tem- 
perature of  from  35  to  50°  C.  ;  it  may  be  ex- 
posed to  the  action  of  diluted  sulphuric  acid 
(1  :  25),  or  the  familiar  mixture  of  nitric  acid 
and  chlorate  of  potash  may  be  used.  We 
would  especially  recommend  the  latter,  parti- 
cularly the  combination  of  80  ccm.  of  nitric 
acid  of  1.16  sp.  wt.  with  an  equal  quantity  of  ,..Fis-  isi.-  Thyroid  car- 

*  •>  tilage  of  the  swine.    The 

distilled  water,  and  the  addition,  at  an  ordi-  ^sis  substance  is  divid- 

'  ed  into  cell-districts   by 


nary  temperature,  of  sufficient  chlorate  of  pot- 
ash  to  saturate.  After  a  few  days  the  desired 
reduction  will  be  obtained,  and  the  appearances  will  be  ren- 
dered very  beautiful  by  tingeing  with  aniline-red  or  carmine. 
According  to  Landois'  experience,  these  arese  are  even  rendered 
distinct  by  tingeing  with  fuchsine  sections  of  cartilage  which 
have  been  deprived  of  their  water  by  means  of  alcohol.  How- 
ever, even  without  any  artificial  interference,  the  central  por- 
19 


290  SECTION    THIRTEENTH. 

tion  of  the  cartilage  of  the  ensif  orm  process  of  the  rabbit  usually 
presents  the  same  appearance  of  the  basis  substance  (Remak). 

There  are  various  means  for  dissolving  the  interstitial  sub-  ' 
stance  of  cartilage.  This  is  effected  by  immersion  for  several 
hours  in  a  concentrated  solution  of  potash.  The  same  object 
may  be  accomplished  by  immersion  for  four  hours  in  sulphuric 
acid  containing  an  atom  of  hydrate  water,  and  the  subsequent 
addition  of  water.  The  means  most  commonly  used,  however, 
is  a  long-continued  boiling  in  water.  "While  the  cartilages  of 
small  embryos  undergo  this  solution  after  several  hours  even  at 
a  moderate  temperature,  the  older  tissues  require,  with  the  ac- 
cess of  air,  to  be  boiled  for  12, 18,  sometimes  24  to  48  hours. 
If  the  cartilage  which  is  being  treated  in  this  manner  be  ex- 
amined at  each  stage  of  its  decomposition,  one  may  recognize 
the  obstinacy  with  which  the  cartilage  cells  themselves  resist 
the  boiling  temperature,  and  that  in  none  of  their  parts  do  they 
contain  any  gelatine-producing  substance.  Even  when  the  en- 
tire basis  substance  is  dissolved  one  may  meet  with  numerous 
cells  floating  in  the  fluid. 

The  capsules  of  the  cartilage  cells  also  resist  the  effects  of 
the  boiling  water  more  energetically  than  the  interstitial  sub- 
stance, so  that  the  chondrogenous  matter  of  the  latter  is  in  no ' 
wise  to  be  regarded  as  being  the  same  as  that  of  the  capsules. 
The  substance  of  reticular  cartilage  shows  the  extraordinary  in- 
solubility of  the  so-called  elastic  tissue. 

Pathological  cartilage  tissue  is  not  a  rare  occurrence.  It  ap- 
pears as  an  inflammatory  new  formation  in  chronic  arthritis 
and  in  the  formation  of  callus ;  but,  as  a  rule,  such  cartilaginous 
tissue  makes  its  appearance  in  the  form  of  tumors,  the  so-called 
enchondromata.  The  textural  conditions  of  such  cartilaginous 
tumors  present  different  appearances,  the  same  as  in  the  normal 
tissue.  Thus  the  basis  substance  may  appear  homogeneous  (and 
this  is  predominantly  the  case),  in  places  it  may  form  an  elastic 
framework,  or,  finally,  it  may  have  a  connective-tissue  char- 
acter ;  not  unf  requently  one  may  meet  with  all  three  of  these 
varieties  of  cartilage  in  the  various  parts  of  one  and  the  same 
enchondroma. 

It  would  be  superfluous  to  enter  further  into  the  considera- 


CONNECTIVE    TISSUE    AND    CARTILAGE.  291 

tion  of  the  methods  of  examination ;  they  are  the  same  as  for 
the  normal  tissue. 

Various  fluids  have  been  recommended  for  preserving  pre- 
parations of  cartilage.  Even  distilled  or  camphor  water  renders 
good  service.  Glycerine  strongly  diluted  with  water  (2  parts 
water,  1  part  glycerine)  also  acts  advantageously,  at  least  in 
many  cases.  Harting  sometimes  employs  creosote  water  (p. 
215),  sometimes  a  solution  of  sublimate  (1  part  to  2-500  water). 
I  have  also  used  the  latter  fluid  with  success.  Furthermore,  the 
sublimate  in  combination  with  phosphoric  acid  (sublimate  1, 
phosphoric  acid  1,  and  water  30)  has  also  been  recommended 
(p.  214).  Cartilage  strongly  tinged  with  carmine  and  deprived 
of  its  water  by  means  of  absolute  alcohol  may  be  mounted  in 
Canada  balsam  with  advantage. 


Section  jTourteentl). 

BONES  AND  TEETH. 

WE  consider  these  two  members  of  the  connective-substance 
group  in  a  special  chapter  because  they  require  peculiar  methods 
of  investigation,  in  consequence  of  their  hardness  and  density. 

There  are  two  kinds  of  preparatory  treatment  of  the  bones 
and  teeth,  according  as  one  desires  to  preserve  these  parts  with 
their  inorganic  elements  or  deprived  of  the  same.  Let  us  first 
speak  of  the  latter. 

Various  acids  are  used  for  decalcifying,  such  as  muriatic  and 
nitric  acids,  also  chromic  acid,  the  latter  partly  pure,  partly 
mixed  with  muriatic  acid  in  order  to  obtain  a  more  energetic 
action.  Small  pieces  of  bones  or  teeth,  placed  in  muriatic  or 
nitric  acid,  lose  their  earthy  salts  in  a  few  days  if  the  fluid  is 
changed  several  times;  chromic  acid  requires  a  longer  time. 
One  should  always  select  high  degrees  of  dilution  (about  5  per 
cent,  of  muriatic  acid),  and  not  begrudge  a  few  days  more,  or 
even  a  whole  week,  if  one  desires  to  spare  the  tissue.  Chromic 
acid,  in  combination  with  a  few  drops  of  hydrochloric  acid 
(p.  132),  deserves  to  be  most  recommended.  The  immersed 
object  will  be  seen  to  become  gradually  paler  and  more  flexible, 
and  finally  to  resemble  cartilage  in  appearance  and  consistence. 
The  action  of  the  acid  is  now  to  be  discontinued,  and  the  bones 
or  teeth  carefully  washed  out  with  water.  The  parts  which 
have  thus  been  decalcified,  or — to  use  a  badly  selected  expression 
—the  bone  and  tooth  cartilages  then  permit  of  the  same  methods 
of  examination  as  cartilage  tissue  proper.  This  method  is  most 
to  be  recommended  for  all  investigations  where  it  is  necessary 
to  obtain  a  large  series  of  views  with  economy  of  time  and  labor. 
Dried  specimens  may  be  decalcified  in  this  manner  as  well  as 
those  which  are  fresh,  taken  directly  from  the  body.  Bones  in 


BONES    AND    TEETH. 


293 


the  latter  condition,  treated  with  chromic  acid,  show  at  the  same 
time  the  substance  which  fills  their  canals  and  cavities,  the 
medulla ;  pyroligneous  acid  accomplishes  the  same. 

Decalcified  in  the  same  manner,  the  texture  of  the  dentine 
and  also  of  the  cement  may  be  well  recognized,  but  not  that  of 
the  enamel,  in  consequence  of  the  considerable  amount  of  min- 
eral elements  which  it  contains. 

Naturally,  more  energetic  measures  are  necessary  if  it  be 
desired  to  isolate  the  walls  of  the  canaliculi  and  lacunse  together 
with  the  cell  remnants,  that  is,  the  bone  corpuscles  of  the  bone 
and  the  dentinal  tubes  of  the  dentine. 

Yirchow  showed  how  to  liberate  the  bone  corpuscles  in  this 
way,  years  ago.  A  thin  piece  is  to  be  removed  from  a  fresh  bone 
and  either  simply  macerated  in  muriatic  acid  or  boiled,  in  a 
decalcified  condition,  in  distilled  water, 
or  (which  is  preferable)  in  a  solution  of 
soda.  A  period  then  arrives  in  which 
the  tissue  assumes  a  pulp-like  softness. 
Preparations  which  are  now  removed 
(fig.  132)  show  us,  especially  if  a  slight 
pressure  be  made  on  the  covering-glass, 
the  bone-corpuscles  together  with  their 
processes  and  nuclei  protruding  from 
the  dissolved  basis  substance.  Occa- 
sionally, some  of  these  may  be  entirely 
isolated  in  this  way  (a  c  d).  That  they 
have  undergone  considerable  changes 
in  consequence  of  this  energetic  treat- 
ment is  sufficiently  obvious. 

Forster  has  made  us  acquainted  with  another  method  of 
isolation  by  means  of  strong  nitric  acid.  Thin  pieces  of  the 
dried  bone  or  tooth  are  to  be  placed  in  concentrated  or  but 
slightly  diluted  nitric  acid,  to  which  a  little  glycerine  is  added. 
The  desired  effect  is  obtained  after  a  series  of  hours,  sometimes 
not  till  the  following  day.  Even  bones  in  which  all  the  soft 
parts  are  destroyed  yield  a  similar  appearance  with  the  same 
treatment  (Neumann). 

A  maceration  in  strong  muriatic  acid,  likewise  a  protracted 


Fig.  132.  Remains  of  the  bone- 
corpuscles  with  their  boundary 
layer,  from  the  decalcified  shaft 
of  the  femur,  after  boiling  in  a 
solution  of  soda,  a  6  c,  corpuscles 
containing  nuclei  (at  6  an  adhe- 
rent residue  of  the  basis  sub- 
stance) ;  d,  a  bone-corpuscle  with 
a  crumbled  nucleus. 


294 


SECTION    FOURTEENTH. 


boiling  of  the  piece  of  decalcified  bone  in  a  Papin's  digester, 
also  causes  the  destruction  of  the  interstitial  substance  and  the 
isolation  of  the  bone-corpuscles  with  their  systems  of  processes. 
Thin  scales  of  bone  fall  to  pieces  after  the  action  of  diluted 
solutions  of  potash  or  soda  for  half  a  day  or  several  hours. 

To  demonstrate  the  bone-cells  proper  (fig.  133),  however, 
very  thin  scales  of  fresh  bone,  and  especially  such  as  are  care- 
fully tinged  with  carmine,  are  necessary.  These  (&),  sur- 
rounded by  the  already  mentioned  elastic  boundary  layer  of 
the  basis  substance  (&),  represent  the  bone-corpuscles  of  the 
foregoing  woodcut. 


Fig.  133.  Bone  cells 
from  the  fresh  eth- 
moid bone  of  the 
mouse,  tinged  with 
carmine,  a,  limiting 
layer ;  6,  cell. 


Fig.  134.  The  Sharpey's  fibres,  6,  of  aperiosteal  lamella 
of  the  human  tibia ;  a  c,  lacunae. 


The  impregnation  with  gold  has  also  been  recommended  for 
the  recognition  of  the  bone-cells.     The  thin  bones  of  the  cra- 
nium of  the  water  salamander,  after  an  immersion  of  from  one 
hour  to  an  hour  and  a  half  in  a  1  per  cent, 
solution,  and  a  subsequent  reduction  in 
acidulated  water,  yield  good  specimens 
in  from  one  day  to  a  day  and  a  half. 
The  adherent  soft  parts  may  be  scraped 
from  the  bone  while  it  is  in  the  gold 
solution.      Even    fragments    of    large 
bones  permit  of  this  treatment  (Joseph). 
The  decalcified  bones  of  man  and  the 
mammalia  are  also  to  be  used  for  de- 
monstrating   the     so-called    Sharpey's 
fibres  (undeveloped  connective-tissue  fibres),  fig.  134. 

The  walls  of  the  dentiiial  tubes  of  dentine  may  also  be  iso- 


Fig.  135.  Two  dentinal  cells, 
6,  which  pass  with  their  pro- 
cesses through  a  portion  of  the 
dentinal  canals  at  a,  and  pro- 
trude from  the  fragment  of  den- 
tine ate;  after  Beale. 


BONES    AND    TEETH.  295 

lated  by  similar  methods.  In  fragments  of  fresh  teeth  oae 
may  see  these  tubes  occupied  by  a  system'of  soft  fibres  (fig.  135, 
c),  which  latter  represent  the  processes  of  the  dentinal  cells  of 
the  tooth-pulp,  or  the  so-called  odontoblasts  (b)  (Tomes). 

An  entirely  different  procedure  is  necessary  for  the  exami- 
nation of  the  calcareous  tissue  of  the  bones  and  teeth.  Thin 
plates  must  be  sawed  from  the  bone  and  ground  on  a  stone 
till  they  have  become  as  thin  as  paper,  and  have  acquired 
the  transparency  necessary  for  their  examination.  The  whole 
procedure  requires  time,  is  troublesome,  and  therefore,  as  a 
rule,  it  is  shunned  by  microscopists.  However,  with  a  little 
perseverance,  one  may  obtain  excellent  and  uninjured  prepara- 
tions. 

The  desired  object  maybe  accomplished  in  various  ways,  and 
there  are  numerous  methods  extant  for  producing  sections  of 
bones  and  teeth.  We  will  here  communicate  to  the  reader  a 
procedure  which  leads  to  the  production  of  very  beautiful 
specimens,  and  the  outlines  of  which  were  given  a  few  years 
ago  by  Reinicke. 

A  fine  saw,  the  blade  of  which  is  made  from  a  watch-spring 
and  is  held  by  screws,  is  employed  for  sawing  out  the  plates  of 
bones  or  teeth.  The  bone  or  tooth  is  to  be  firmly  secured  in  a 
vice.  Brittle  objects  which  are  liable  to  splinter  are  to  be  previ- 
ously wrapped  in  paper. 

After  sawing  out  the  plate,  it  is  to  be  ground  on  a  small 
rotary  grindstone,  the  handle  of  which  is  to  be  turned  by  the 
left  hand  while  the  plate  is  pressed  by  the  fingers  of  the  right 
hand  on  one  of  the  flat  surfaces  of  the  stone.  The  stone  is  to 
be  kept  moistened  by  means  of  a  trough  placed  under  it  con- 
taining water.  If  this  tolerably  inexpensive  apparatus  is  not  at 
hand,  the  first  excess  may  also  be  removed  with  a  file. 

In  order  to  obtain  a  smooth  surface,  the  thin  preparation  is 
now  to  be  placed  on  a  fine  flat  whetstone,  such  as  is  used  for 
sharpening  razors  ;  in  this  way,  held  by  the  fingers,  it  may  be 
further  ground  on  both  surfaces.  This  may  also  be  accom- 
plished between  two  such  whetstones,  and  indeed  more  rapidly. 
Small  objects  are  to  be  previously  cemented  011  to  a  glass  plate 
with  Canada  balsam  ;  ether  serves  best  for  loosening  the  bone 


296 


SECTION    FOUKTEEOTH. 


and  for  removing  the  remains  of  the  balsam.  The  bone  may 
also  be  very  conveniently  cemented  with  red  sealing-wax,  and 
the  adequate  thinness  of  the  section  may  finally  be  recognized 
bv  the  liveliness  with  which  the  red  shines  through  it.  The 

«•  n 

sealing-wax  is  to  be  dissolved  with  strong  alcohol.  The  pre- 
paration is  then  to  be  cleaned  in 
water,  either  with  a  camel's-hair 
brush  or  a  soft  tooth-brush,  and 
dried.  If  the  grain  of  the  whet- 
stone is  sufficiently  fine,  nothing 
further  is  necessary.  If  one  de- 
sires to  obtain  a  better  polish, 
i  one  may  employ  a  glass  plate  or 
a  piece  of  soft  leather  wrhich  is 
nailed  to  a  flat  strip  of  wood,  and 
which  is  smeared  with  tripoli  or 
some  other  polishing  powder.  A 
beautiful  polish  may  also  be  pro- 
duced in  a  short  time  with  fine 
emery  paper.  A  preparation  ob- 
tained in  this  way — for  example, 
e  a  transverse  section  (fig.  136) — 
•  presents  a  charming  appearance. 
The  various  general  or  funda- 
mental lamellae  (a  d  b)  may  be 
recognized  passing  throughout 
the  entire  bone,  and  the  trans- 
verse sections  of  the  Haversian 
canals  with  their  special  lamellae 
(c)  surrounding  them,  as  well  as 

Fig.  136.   Transverse  section  of  a  human  the    innumerable    SO    COnSplCUOUS 

meta  carpal  bone,      a,  external,     &,  internal  1  .  .         ,  , .       , .      , 

surface;   d,   interstitial  lamellas ;   c,  Haver-  laClin33    With    their    CanallCUll     (6) 

sian  canals  in  transverse  section  with  their 

lamellar  systems;  e,   lacunae  and  canaliculi  may  alSO   D6  Seen. 

containing  air.  JL 

To  obtain   these  appearances, 

however,  the  latter  system  of  canals  must  be  dry  and  filled  with 
air.  A  section  which  is  sufficiently  thin  presents  this  appear- 
ance without  any  addition,  and  in  this  condition  it  may  enter 
the  collection  as  a  permanent  preparation.  Yery  handsome 


BONES    AND    TEETH. 


297 


preparations  are  obtained  by  melting  the  sections  into  a  resi- 
nous substance.  Ordinary  fresh  Canada  balsam  is  not  adapted 
for  this  purpose,  as,  in  consequence  of  the  slowness  with  which 
it  hardens,  the  air  escapes  more  or  less  completely  from  the 
section.  In  order  to  obtain  a  good  medium  for  mounting,  pro- 
ceed in  the  following  manner: — A  quantity  of  fresh  Canada 
balsam  is  to  be  poured  into  a  watch-glass,  and  placed,  with  a 
bell-glass  over  it,  on  a  warm  stove  for  several  days,  until  the 
Canada  balsam  has  become  quite  hard  and  solid.  With  this, 
and  by  strongly  heating  the  glass  slide,  the  sections  of  bones 
and  teeth  may  be  mounted  without  displacing  the  air,  especially 
if  the  preparations  are  exposed  to  the  cold  immediately  after- 
wards. 


Fig.  137.  Portion  of  a  transverse  section  of  the  shaft  of  the  humerua,  treated  with  oil  of  tur- 
pentine. «,  Haversian  canals ;  b,  their  lamellar  systems ;  c,  newly-deposited  osseous  substance ; 
d,  lacunae. 

If,  on  the  contrary,  it  be  desired  to  bring  the  lacunae  and 
canaliculi  filled  with  fluid  into  view,  in  the  form  of  cavities, 


298  SECTION    FOUKTEENTH. 

oil  of  turpentine  is  to  be  used  in  the  examination;  and  for 
mounting  permanently,  fresh  fluid  Canada  balsam.  Tingeing 
with  carmine  may  precede  as  a  useful  accessory  (fig.  137). 

In  order  to  fill  the  blood-vessels,  which  is  not  very  easy,  the 
gelatine  may  be  injected  by  a  large  vessel  (in  small  animals),  or 
by  the  nutritive  artery  (in  larger  creatures). 

Injected  bones,  decalcified  slowly  and  conservatively  in  dilute 
chromic  acid,  may  be  examined  and  preserved  in  Canada  bal- 
sam or  in  glycerine.  For  such  purposes  one  should  select  a 
durable  coloring  material.  Bones  injected  with  soluble  Prus- 
sian blue  have  afforded  me  very  handsome  preparations.  It  is 
advisable  to  brush  out  the  cavities  a  little. 

We  are  indebted  to  Gerlach  for  a  method  of  filling  the  cavi- 
ties of  the  lacunae  and  canaliculi  with  coloring  material,  and 
thus  demonstrating  their  hollow  character  in  the  most  percep- 
tible manner.  A  transparent  coloring  material,  and  one  of  the 
smaller  long  bones  which  has  been  sufficiently  macerated  and 
deprived  of  its  fat,  should  be  used.  A  hole  is  to  be  made  in 
the  epiphysis  for  the  reception  of  the  canule,  and  the  entire 
surface  of  the  bone  is  to  be  covered  with  shellac,  so  that  the  in- 
jection fluid  may  not  escape  from  the  apertures  of  the  Haver- 
sian  canals. 

In  order  to  recognize  the  double  refraction  of  the  uniaxal 
negative  bone,  undecalcified  sections  are  to  be  sawed  out  as  ac- 
curately as  possible  in  the  transverse  or  vertical  direction.  They 
should  be  neither  too  thin  nor  too  thick,  but  should  be  rendered 
strongly  transparent  by  means  of  Canada  balsam  or  turpentine. 
If  we  have  a  suitable  transverse  section,  in  which  the  diameter 
of  the  Haversian  canals  is  perpendicular  to  the  long  axis  of  the 
bone,  we  may  recognize,  by  polarized  light,  a  regular  and  ele- 
gant cross,  which  is  not  changed  by  rotation.  However,  only  a 
minority  of  the  bone  sections  fulfil  these  requirements  suffi- 
ciently. Yery  beautiful  appearances  are  obtained  by  the  inter- 
calation of  suitable  films  of  selenite  or  mica.  The  reader  will 
find  further  details  in  Valentine's  work. 

In  investigating  carious  teeth,  they  may  be  broken  to  pieces  in 
a  vice,  as  recommended  by  Neumann,  and  then  sections  made 
from  the  portions  which  have  become  brown  and  deprived  of 


BONES    AND    TEETH. 


299 


their  lime  salts.  But  if  one  desires  to  follow  tlie  transition 
from  healthy  to  diseased  tissue  more  closely,  the  previous  decal- 
cification  is  to  be  recommended.  Tingeing  with  carmine  and 
iodine  also  renders  good  service. 

It  is  much  more  troublesome  to  prepare  the  enamel  of  the 
teeth  than  bones  and  dentine  for  examination.     It  is  preferable 


Fig.  139.  Transverse 
section  of  human  enam- 
el prisms. 


Fig.  138.  Vertical 
section  of  a  human 
incisor  tooth. 


Fig.  140.  Side  view  of  hu- 
man enamel  prisms. 


to  use  only  young  teeth  in  a  fresh  condition ;  much  care  should 
be  taken  in  sawing,  and  still  more  in  grinding.  Dried  teeth 
may  be  rendered  serviceable  again  by  soaking  them  for  several 
days  in  water.  Longitudinal  and  transverse  sections  of  the 
enamel  prisms  (figs.  139, 140)  may  be  recognized  in  good  speci- 
mens. The  transverse  lines  of  the  enamel  may  be  best  seen  by 
moistening  the  object  with  muriatic  acid.  Developing  teeth  are 
to  be  used  for  isolating  the  enamel  prisms. 

The  dental  pulps  are  to  be  examined  in  fresh  teeth;  they  are 
to  be  liberated  by  breaking  the  teeth ;  in  a  vice  or  by  the  blow 
of  a  hammer.  Teeth  carefully  decalcified  by  means  of  chromic 
acid  and  then  hardened  in  alcohol  also  afford  very  good  views 


300  SECTION   FOURTEENTH. 

especially  in  transverse  sections.  We  shall  speak  of  the  nerves 
further  on. 

With  regard  to  the  so  difficult  and  complicated  histological 
relations  of  the  development  of  the  teeth,  we  must  refer  to  the 
text-books.  As  material  for  examination,  may  be  selected  em- 
bryos from  the  third  to  the  sixth  month  of  foetal  life,  likewise 
those  of  the  mammalia,  as  for  example  of  the  hog,  or,  among  the 
carnivora,  of  the  dog  and  cat ;  they  should  be  immersed  in 
chromic  acid.  The  new-born  may  also  be  used  with  advantage. 
It  is  preferable  to  immerse  only  the  jaw.  The  finest  specimens 
are  obtained  by  a  very  gradual  decalcification,  occupying  sev- 
eral weeks,  by  means  of  chromic  acid  solutions  of  0.1-0.3  per 
cent.,  which  must  be  frequently  changed.  A  5  per  cent,  solu- 
tion of  the  officinal  nitric  acid  is  also  very  highly  praised  for 
this  purpose  by  Boll.  Fine  sections  are  to  be  made  with  a 
razor,  in  various  directions,  through  the  jaw  thus  softened,  and 
examined  in  glycerine.  Canada  balsam  is  to  be  recommended 
for  mounting  permanent  preparations  after  tingeing  with  car- 
mine. 

The  examination  of  developing  bone  is  not  less  difficult.  Al- 
though twenty  years  ago,  in  consequence  of  the  incompleteness 
of  the  methods  of  investigation  at  that  period,  the  osteogenetic 
process  could  scarcely  be  found  out,  we  have  succeeded  more 
recently,  by  the  aid  of  improved  methods,  in  unfolding  the 
chief  points,  at  least,  of  the  textural  conditions  which  here 
occur. 

The  various  portions  of  the  skeleton  are  divided  into  such  as 
are  preformed  in  a  cartilaginous  state,  and  others  in  which  such 
a  cartilaginous  preformation  cannot  be  recognized.  We  have 
finally  ascertained,  through  modern  researches,  that  in  the  for- 
mer the  cartilage  does  not  become  transformed  into  bone  sub- 
stance, as  was  considered  to  be  the  case  at  a  former  period ;  but 
rather  that  the  cartilaginous  tissue  disappears  in  consequence  of 
the  formation  of  vessels  and  the  deposition  of  bone  salts,  and 
that  in  the  spaces  formed  by  its  dissolution  the  bone  substance 
appears  as  a  secondary,  newly  formed  tissue. 

Cartilage  which  is  destined  to  give  place  in  this  manner  to 
the  bone  substance  is  seen  to  be  permeated  by  canals  filled  with 


BONES    AND    TEETH. 


301 


small  cells,  and  in  which  the  development  of  blood-vessels  takea 
place.  This  observation  is  in  general  easy  to  make  in  a  few 
sections  of  foetal  bone  cartilage.  If,  as  is  at  present  the  custom, 
the  embryos  of  man  and  the  mammalial  animals  which  have 
been  immersed  in  chromic  acid  are  made  use  of,  the  blood-cells 
will  not  unfrequently  be  recognized  in  glycerine  preparations 
as  a  reddish-brown  mass  filling  these  newly  developed  vessels. 
The  so-called  points  of  ossification  then  make  their  appear- 
ance ;  that  is,  those  places  in  the  cartilaginous  skeleton  where 
numerous  calcareous  granules  lie  embedded  in  the  interstitial 
substance  (fig.  141  a),  and  where  the  solution  and  melting  down 


Fig.  141.  The  las*  dorsal  and  first  lumbar  vertebra  of  a  human  foetus  of  ten  weeks  in  vertical 
section,  a,  calcified,  &,  soft  cartilage  ;  c,  oblong  cells  at  the  periphery  of  the  developing  symphy- 
sis ;  d,  remains  of  the  chorda  dorsalis  becoming  transformed  into  the  gelatinous  nucleus  of  the 
vertebral  symphysis. 

of  the  cartilage,  which  soon  commences,  begins.  Chromic  acid 
preparations  are  also  exceedingly  well  adapted  for  this  purpose, 
as,  after  the  decalcification,  the  places  in  question  still  remain 
recognizable  by  their  cloudy  appearance  and  the  irregular  consti- 
tution of  the  interstitial  substance  ;  but  it  is  only  by  the  use  of 
glycerine  that  they  obtain  such  a  degree  of  transparency  that 
the  processes  in  question  can  be  investigated  in  all  their  details. 
By  the  aid  of  similar  methods — and  we  here  most  urgently 
recommend  tingeing  with  carmine — the  later  stages  of  the  pro- 
cess are  also  to  be  followed  (figs.  142  and  143),  such  as  the  more 


302 


SECTION    FOURTEENTH. 


and  more  preponderating  formation  of  cavities  in  the  cartilagi- 
nous skeleton  (a  b  df)  in  consequence  of  the  continued  melting 
down  of  the  tissue  of  the  cartilage,  the  progressing  calcification 
of  the  cartilage  at  the  periphery,  the  formation  of  daughter- 
cells,  etc.,  concerning  which  the  text-books  on  histology  are  to 
be  consulted. 


Fig.  142.  A  phalangeal  epiphysis  of  the  calf,  cut  perpendicularly  through  fts  ossifying  border. 
At  the  upper  part  the  cartilage  with  its  irregular  capsules  containing  daughter-cells,  a.  Smaller 
medullary  spaces  penetrating  the  cartilage,  in  part  without  visible  entrance ;  6,  the  same  contain- 
ing cartilage  marrow-cells ;  c,  remains  of  the  calcined  cartilage  ;  rf,  larger  medullary  spaces,  on  the 
walls  of  which  the  newly-formed,  partly  thin  and  unstratified.  partly  thicker  and  lamellated  bone 
tissue  is  deposited ;  e,  a  developing  bone-cell ;  /,  an  opened  cartilage  capsule  with  an  embedded  bone- 
cell  ;  fif,  a  partially  filled  cavity,  covered  externally  with  bone  substance  and  containing  a  marrow- 
cell  ;  h,  numerous  apparently  closed  cartilage  capsules  with  bone-cells. 

If  the  sections  are  brushed  out  a  little,  the  newly-formed 
bone  substance  may  be  noticed  in  the  form  of  a  homogeneous 
layer  (figs.  142  d  d,  143  ft)  covering  the  walls  of  the  cavities,  to- 


BONES   AND    TEETH. 


303 


gether  with  the  young  bone-cells  (e),  which  are  at  first  thin,  soft, 
and  unstratified,  afterwards  thicker,  stratified,  and  diffusely  cal- 
cified in  the  outer  layers. 

The  recognition  of  the  origin  of  the  bone-cells  requires  a  more 
accurate  examination,  and  a  careful  analysis  of  the  cell  forma- 
tions which  occupy  the  cavities. 

These  (figs.  142  £  J  and  144  &),  generally  regarded  as  deriva- 
tives from  the  daughter-cells  of  the  perishing  cartilage  tissue, 
are  seen  by  the  naked  eye  as  a  soft,  reddish  mass,  and  appear  in 
the  form  of  lymph-cells  as  roundish,  small,  and  granulated,  with 
a  simple  or  double  nucleus.  Many  assume  spindle  and  stellate 
shapes  (c  c)  to  become  transformed  into  connective-tissue  cells, 
others  form  capillary  vessels,  others  again,  with  a  proportionate 
increase,  probably  become  at  a  later  period  enlarged  in  size  and 
transformed  into  the  globular  fat-cells  of  the  bone-marrow 
(d  e).  If  attention  be  directed  to  the  periphery  of  these  cellu- 


Fig.  143.  Transverse  section  from  the  up- 
per portion  of  the  femur  of  a  human  embryo 
at  the  llth  week,  a.  Remains  of  cartilage ;  &, 
covering  of  osteoid  tissue. 


Fig.  144.  Cartilage  marrow-cells,  a, 
from  the  humerus  of  a  5-months  human 
foetus ;  6,  from  the  same  bone  of  the  new- 
born ;  c,  star-shaped  cells  of  the  former 
melting  down  into  fibrous  formations ;  rf, 
formation  of  the  fat-cells  of  the  marrow ; 
e,  a  cell  filled  with  fat. 


lar  contents,  especially  in  thin  sections  which  have  been  slightly 
and  cautiously  brushed,  a  layer  of  peculiar  cells  will  be  seen 
closely  pressed  together,  which  differ  somewhat  from  the  ordi- 
nary marrow-cells  and  remind  one  of  epithelium  (fig.  145  c). 
From  these,  the  "  osteoblasts "  of  Gegenbaur,  the  separation 
of  the  basis  substance  of  the  bone  tissue  takes  place  in  an  out- 
ward direction,  and  some  of  these  cells,  advancing  beyond  the 


304 


SECTION   FOURTEENTH. 


crowded  ranks,  sink  into  this  tissue  (g)  to  grow  in  a  radiated 
manner  and  become  bone-cells  (f). 

Fig.  142,  d,  e,  shows  such  cells  commencing  to  assume  the 
stellate  form ;  some  of  them  are  already  entirely  surrounded  by 
a  homogeneous  interstitial  substance,  others  have  only  a  portion 
of  their  surface  (that  which  is  directed  outwards)  covered  in  this 


manner. 


Fig.  145.  Transverse  section  from  the  femur  of  a  human  embryo  of  about  11  weeks,  a,  a  trans- 
verse, and  &,  a  longitudinally  divided  medullary  canal ;  c,  osteoblasts  ;  d,  the  more  transparent, 
younger ;  e,  the  older  bone  substance ;  /,  lacunae  with  the  cells ;  g,  cell  still  united  to  the 

osteoblast. 


The  continued  formation  of  new  cavities  in  the  remaining 
portions  of  the  cartilage  causes  the  opening  of  numerous  car- 
tilage capsules.  These  spaces  are  also  soon  occupied  by  bone- 
cells  and  intercellular  masses.  If  the  entrance  of  a  cavity  filled 
in  this  manner  with  young  bone  substance  (fig.  142  f)  be  recog- 
nized, the  appearance  is  easy  to  comprehend.  This  aperture 
is,  however,  much  more  frequently  not  to  be  seen  (h  A),  and 
then  it  makes  an  impression  as  if  there  were  bone  corpuscles 
lying  in  the  interior  of  unopened  cartilage  capsules.  Earlier 


BONES    AND    TEETH.  305 

observers  had  frequently  met  with  such  appearances  in  their 
investigations,  and  were  thus  led  to  the  erroneous  conclusion 
that  (after  the  manner  of  the  formation  of  the  porous  canals  in 
plants)  the  cell  remains  of  the  unevenly  thickening  cartilage 
capsule  became  transformed  into  bone  corpuscles.  Very  in- 
structive examples  of  these  apertures  in  the  cartilage  capsules 
may  be  obtained  from  the  comparison  of  a  series  of  consecu- 
tive transverse  sections  (Miiller).  However,  the  question  as  to 
whether  the  bone-cells  occur  in  ruptured  cartilage  capsules  only, 
and  not  in  those  which  still  remain  closed,  is  one  which  is  not, 
as  yet,  definitely  solved. 

The  later  phases,  the  increasing  deposition  of  new  bone- 
lamellse,  and  the  final  melting  down  of  the  last  remains  of  the 
cartilage  (figs.  142  0, 143  a),  may  also  be  investigated  by  the  aid 
of  the  above-mentioned  methods.  Tingeing  with  carmine  should 
be  invariably  employed  when  it  is  necessary  to  distinguish  the 
already  diffusely  calcified  older  bone  tissue  from  that  which  is 
quite  young  and  still  soft.  The  soft  (osteogenous)  bone  substance 
readily  assumes  a  lively  red  color,  while  the  older,  calcified 
(osteoid)  takes  up  the  coloring  matter  less  readily  and  much 
more  slowly,  even  in  cases  where  a  considerable  portion  of  the 
bone  ^alts  have  been  removed  by  means  of  chromic  acid.  This 
method  is  also  excellent  for  the  inverted  process,  for  the  normal 
as  well  as  the  pathological  decalcification  and  melting  down  of 
bone-tissue. 

To  demonstrate  the  manner  of  growth  of  foetal  or  young 
bones,  longitudinal  and  transverse  sections  should  be  made 
from  those  which  have  been  decalcified.  In  the  former  we 
see  the  growth  in  length  taking  place  at  the  expense  of  the 
cartilaginous,  articular  portion,  and  showing  the  same  struc- 
tural changes  which  we  have  just  mentioned  in  discussing  the 
primary  formation  of  bone. 

Transverse  sections  which  are  to  be  tinged  with  carmine 
deserve  the  preference,  as  a  rule,  for  studying  the  manner  in 
which  bones  increase  in  thickness.  This  takes  place  by  the 
formation  of  a  new  osteogenous  tissue  (fig.  146  e)  from  the  con- 
nective tissue  of  the  periosteum  (a  #)  with  the  help  of  a  similar 

layer  of  osteoblasts  (c).     To  these  is  due  the  elegant  and  regular 
20 


306 


SECTION    FOUETEENTH. 


structure  which  the  bone  assumes  after  the  melting  down  of 
the  primary,  irregularly  deposited  osteoid  substance. 


Fig.  146.  Formation  of  secondary  bone  substance.  Longitudinal  section  through  the  femur 
of  an  older  foetus  of  the  sheep,  a,  the  inner  surface  of  the  periosteum,  consisting  of  connective 
tissue ;  6,  the  younger,  or  OUier's  layer  of  the  periosteum ;  c,  the  stratum  of  osteoblaats ;  d,  newly- 
formed  bone  tissue ;  e,  bone  cavities  and  cells. 

The  bones  of  the  second  group,  originating  from  connective- 
tissue  substance,  without  a  cartilaginous  preformation,  coincide 
very  nearly  with  the  periosteal  mode  of  growth  and  require  the 
same  methods  for  their  examination.  Decalcification  by  means 
of  chromic  acid  and  subsequent  tingeing  with  carmine  has 
afforded  rne  the  best  specimens.  Pyroligneous  acid,  as  recom- 
mended by  Billroth,  may  also  be  employed  with  advantage, 
as  a  few  trials  have  shown  me. 

If  one  fortunately  succeeds  in  injecting  the  embryos  destined 
for  such  examinations  with  transparent  masses,  many  things 
will  be  better  recognized  in  this  case,  as  in  the  investigation 
of  all  osteogenetic  processes,  than  when  the  blood-vessels  are 
not  filled.  The  use  of  warm  water,  in  the  manner  indicated 


BOXES    AND    TEETH.  307 

at  p.  280,  to  cause  the  interstitial  substance  to  assume  a  soft 
pulpy  condition,  deserves  a  further  trial,  as  it  will  probably 
in  this  case,  as  in  that  of  ripe  bones,  render  the  cells  sharper 
and  more  distinct. 

For  the  examination  of  the  bone-marrow,  the  preparatory 
hardening  methods  with  chromic  acid,  bichromate  of  potash, 
and  Miiller's  fluid  may  be  employed.  The  fresh  tissue,  with 
indifferent  fluid  media,  is  also  to  be  recommended.  Here,  for 
instance,  in  tadpoles,  the  vital  changes  of  form  of  the  bone- 
marrow  cells  may  be  readily  appreciated  (Bizzozero).  In  this 
way  numerous  lymphoid  cells  which  are  undergoing  trans- 
formation into  red  blood  corpuscles  may  be  seen  in  the  red 
bone-marrow  of  mammalia!  animals.  This  source  of  the  latter 
cells  was  not  noticed  till  quite  recently  (Bizzozero,  Neumann). 
We  have  already  mentioned  this  circumstance,  in  a  cursory 
manner,  at  p.  230.  The  idea  that  our  cells  pass  through  the  thin 
walls  into  the  vessels  of  the  bone-marrow  is  obvious. 

"With  regard  to  the  ossification  of  permanent  cartilage  which 
occurs  in  the  later  periods  of  life,  such  as  those  of  the  ribs  and 
many  of  those  of  the  larynx,  this  may,  as  a  rule,  be  considered 
as  a  calcification  of  the  cartilage,  which  is  the  same  process  that 
takes  place  on  a  more  extensive  scale  in  the  foetal  skeleton,  and 
never  ceases  entirely  at  any  period  of  life.  As  in  the  embryo, 
so  also  in  the  aged,  the  calcified  cartilaginous  tissue  may  be 
absorbed,  and  osteogenous  substance  deposited  in  the  cavities 
thus  formed. 

The  examination  of  rachitic  bones  constitutes  an  interesting 
study,  completing  that  of  the  normal  foetal  bone  formation. 
The  appearances  naturally  vary,  according  to  the  grade  of  the 
disease,  the  attempts  at  restoration  which  have  taken  place,  etc. 
The  individual  parts  of  a  bone  also  present  numerous  variations. 

An  insufficient,  occasionally  almost  entirely  wanting  calcifica- 
tion of  the  cartilages,  the  persistence  of  considerable  portions 
of  the  foetal  cartilage,  together  with  peculiar  transformations  of 
its  capsules,  and  an  osteogenous  substance  which  is  sometimes 
inadequately,  sometimes  not  at  all  impregnated  with  bone  earths 
may,  in  general,  be  regarded  as  the  chief  anomalies. 

In  the  rachitic  cartilaginous  skeleton  the  medullary  cartilage 


308  SECTION   FOURTEENTH. 

cells  are  met  with  the  same  as  in  normal  bones,  as  also  a  similar 
rupture  of  the  cartilage  capsules  and  the  deposition  of  bone-cells 
with  their  interstitial  substance.  Even  in  the  medullary  spaces, 
anomalies  of  form  and  extent  may  be  seen.  They  frequently  ad- 
vance beyond  the  calcifying  border  of  the  cartilage  and  even  to 
a  considerable  distance  into  the  unaltered  portion  of  the  latter. 
Very  deceptive  appearances  are  presented  by  the  capsules  in 
that  portion  of  the  cartilage  which  remains  ;  in  consequence  of 
the  thickening  of  their  walls,  the  residue  of  their  contents  may 
be  recognized  as  star-shaped  bodies.  Appearances  are  caused 
in  this  manner  which  bear  great  resemblance  to  bone  corpuscles 
and  which,  in  fact,  can  scarcely  be  distinguished  from  many 
ruptured  capsules  in  which  true  bone  corpuscles  are  embedded, 
unless  the  point  of  entrance  happens  to  lie  in  the  plane  of  the 
section.  Hence  we  shall  readily  comprehend  that  until  within 
a  few  years  rachitic  bones  were  regarded  as  affording  the  most 
certain  proof  of  the  transformation  of  cartilage  cells  into  bone 
corpuscles,  and  were  accepted  as  true  paradigms  of  the  process 
of  ossification.  In  reality,  however,  they  constitute  very  insidi- 
ous and  deceitful  objects. 

These  few  remarks  must  suffice,  in  consequence  of  the  narrow 
limits  of  our  little  work.  The  investigations  of  Bruch,  Kolli- 
ker,  Yirchow,  and  Miiller  are  to  be  consulted  for  further  de- 
tails. 

Fresh  bones  or  those  preserved  in  alcohol  may  be  selected  for 
examination.  Those  which  have  been  dried  also  occasionally 
afford  very  handsome  specimens.  Miiller  found  the  employ- 
ment of  weak  solutions  of  chromic  acid,  with  the  subsequent 
addition  of  glycerine,  very  useful  in  these  cases. 

In  consequence  of  the  exuberant  vitality  of  bones,  new  forma- 
tions of  osteogenous  tissue,  physiological  as  well  as  pathological, 
are  of  very  extensive  occurrence.  In  both  cases  the  point  of 
origin  of  the  new  bone  tissue  may  be  from  the  periosteum  and 
the  endosteum,  that  is,  the  connective-tissue  layer  which  lines 
the  medullary  cavity.  The  former  is,  however,  much  more  fre- 
quently the  case,  and  Ollier's  interesting  experiments  show  that 
the  living  periosteum  is  not  deprived  of  its  bone-producing 
power  by  transplantation  to  a  remote  part  of  the  body. 


BONES    AND    TEETH.  309 

A  beautiful,  accurately-investigated  example  of  this  double 
origin  is  afforded  by  the  reunion  of  fractured  bones,  the  so-called 
callus  formation.  If  the  examination  be  made  with  the  aid  of 
the  methods  at  present  used  for  the  normal  osteogeiiesis,  the 
newly-formed  osteogenous  substance  which  has  originated  in  the 
periosteum  may  be  seen  surrounding  the  ends  of  the  bones  like 
a  ring.  Beneath  the  periosteum,  which  is  here  thickened  and 
swollen,  appear  the  various  layers  of  osteogenous  tissue  which 
are  formed  from  it.  In  man  these  strata  have,  as  a  rule,  a  con- 
nective-tissue character,  much  less  frequently  that  of  cartilage 
(while  in  mammalial  animals,  under  similar  conditions,  there  is 
a  more  plentiful  production  of  cartilage).  Secondly,  there  is  a 
reunion  of  the  bone  tissue  beneath  the  endosteum.  The  letter 
also  swells  up  and  produces  new  osteogenous  tissue,  which 
spreads  through  the  medullary  cavity  and  plugs  it  up. 

Where  there  is  a  greater  loss  of  substance  in  a  bone,  the  re- 
generation takes  place  from  the  periosteum. 

Other  new  formations  of  bone  tissue,  such  as  the  hypertro- 
phies or  hyperostoses,  the  inflammatory  productions  of  the  same 
and  the  bone  tumors  originate  in  part  and  chiefly  from  the  peri- 
osteum, in  part  from  the  connective  tissue  of  the  medullary 
cavity. 

Hyperostosis  is,  in  reality,  exactly  the  same  occurrence  which 
is  met  with  in  the  increase  in  thickness  of  young  bones,  and,  in 
suitable  transverse  sections,  it  presents  very  similar  appearances. 
The  local,  more  or  less  salient  new  formations  of  bone  substance 
of  this  kind,  which  are  not  separated  from  the  ordinary  tissue  by 
any  line  of  demarcation,  constitute  the  compact  exostoses. 
Next  to  these  come  the  tumors  which  are  composed  of  a  denser 
bone  tissue.  They  show,  in  part,  the  ordinary  compact  texture ; 
in  many  cases  they  are  of  a  more  spongy  nature ;  in  others, 
finally,  they  have  an  ivory-like  hardness,  in  consequence  of  the 
slight  development  of  medullary  canals.  The  osteophytes  have 
a  sponge-like  arrangement. 

The  cases  hitherto  mentioned  have  placed  before  the  reader 
bone  tissue  formed  from  the  periosteum.  In  the  so-called  scle- 
roses of  bones  we  meet  with  the  new  formation  of  osteogenous 
tissue  proceeding  from  the  medullary  cavities  and  the  medullary 


310  SECTION    FOURTEENTH. 

canals.  Among  the  osteosarcomse,  the  central  ones  are  devel- 
oped from  the  large  medullary  cavity,  the  peripheral  ones  from 
the  periosteum.  They  show,  in  the  main,  only  isolated  globular 
and  flake-like  masses  of  bone  tissue,  without  vessels  or  medul- 
lary canals. 

The  new  formation  of  osteogenous  substance  in  soft  tissues, 
independent  of  preexisting  bone,  has  certainly  been  very  much 
exaggerated  in  favor  of  the  modern  connective  substance  theory. 
In  most  cases  there  is  only  calcified  connective  tissue  with  in- 
dented corpuscles.  However,  the  production  of  true  bone  sub- 
stance in  connective  tissue  parts  does  take  place,  although  rare- 
ly. The  stratified  arrangement  of  the  basis  substance,  and  the 
radiated  bone  corpuscles,  connected  with  each  other  by  their 
branches  in  a  reticular  manner,  secure  one  against  mistaking 
the  one  for  the  other. 

The  resorption  of  the  previously  decalcified  bone  tissue  con- 
stitutes the  opposite  process.  In  normal  life  the  melting  down 
of  the  bone  substance  occurs  very  extensively  in  growing  young 
bones.  Only  call  to  mind  the  formation  of  the  larger  medullary 
cavities  in  the  foetus,  and  the  Haversian  spaces  of  later  periods ! 
The  anatomical  events  which  take  place  here  are  the  increase  of 
the  medullary  cells  and  the  enlargement  of  the  medullary 
spaces,  the  crumbling  down  and  fatty  degeneration  of  the  bone- 
cells  together  with  the  decalcificatioii  of  the  neighboring  osteoid 
substance  and  the  subsequent  dissolution  of  the  same.  Hereby 
the  liquefying  bone  tissue  frequently  shows  excavated  borders, 
as  if  gnawed  out.  If  such  a  condition  occurs  at  a  later  period 
as  an  abnormal  process,  we  have  the  so-called  osteoporosis. 
Osteo-malacia  also  presents  us  with  a  similar  increase  of  medul- 
lary cells  and  medullary  spaces,  with  impoverishment  of  the 
osteoid  substance  in  bone  earths,  and  the  dissolution  of  the  same. 
In  reality  the  same  process  occurs  in  the  formation  of  granula- 
tions. While,  however,  in  this  case  the  interstitial  substance  of 
the  granulating  medullary  cells  still  presents  a  certain  firmness, 
similar  to  the  ordinary  consistence  of  foetal  bone  tissue,  in  other 
cases  there  may  be  a  liquefaction  of  the  interstitial  mass.  The 
cells  which  are  suspended  in  such  a  fluid  are  then  called  pus 
corpuscles,  and  the  process  itself  is  called  caries.  The  latter, 


BONES    AND    TEETH.  311 

corresponding  to  the  two  localities  of  the  osteogenesis,  may  either 
occur  within  the  bone,  in  its  medullary  cavities,  or  externally  in 
the  canals  which  are  filled  with  bone  marrow  by  the  periosteum. 
Thus  the  microscope  here  teaches  in  a  very  beautiful  manner 
how  normal  and  pathological  processes  may  pass  over  into  each 
other. 

Decalcified  bone  substance  is  said  by  many  histologists  to  be 
capable  of  transformation  into  ordinary  connective  tissue. 
According  to  our  views,  this  is  incorrect.  This  substance  is 
incapable  of  any  future  development  j  it  simply  undergoes 
liquefaction,  sooner  or  later. 

Finally,  if  inquiry  be  made  as  to  the  methods  of  examining 
diseased  bones,  reference  is  to  be  made  to  what  has  already 
been  remarked.  They  are  the  same  as  for  the  normal  tissue. 
Dried  bones  are  less  to  be  recommended  than  moist  ones,  which 
may  be  decalcified  by  means  of  chromic  acid  with  the  addition 
of  a  little  muriatic  acid,  and  which  may  be  subsequently  hard- 
ened again,  according  to  circumstances,  in  strong  alcohol. 
Bones  which  are  strongly  impoverished  in  bone  earths  may  be 
examined  fresh,  or  as  alcohol  preparations,  without  the  use  of 
acids.  As  we  have  already  remarked,  the  decalcified  tissue 
distinguishes  itself  in  a  very  beautiful  manner  from  that  which 
is  still  calcified  by  the  readiness  with  which  it  imbibes  carmine. 


Section  Jftfteentt). 


MUSCLES  AND  NERVES. 

MUSCLES  and  nerves,  in  consequence  of  their  softness,  require 

very  different   accessories  than 

/x\  the  hard  tissues  which  we  have 

/   a.    If  just  left. 

Ql  \  /  r^1Q  muscillar  tissue  of  man 

and  the  vertebrate  animals  con- 
sists of  two  forms  of  fibres, 
the  smooth  and  the  transversely 
striated. 

The  latter  muscles  show  as 
their  elementary  formation  a 
generally  undivided,  more  rare- 
ly branched  fibrilla,  which  is 
marked  with  fine  and  closely 
arranged  transverse  lines  (the 
so  -  called  primitive  bundle), 
while  the  smooth  muscles  are 
formed  of  spindle-shaped,  lin- 
early arranged  cells.  With  this 
difference  in  structure  is  also 
associated  differences  in  their 
manner  of  action.  The  smooth 
muscles  of  man  always  act  in- 
voluntarily and  slowly ;  the 
transversely  striated  muscles, 


Fig.  147.  smooth  muscular  tissue,  a,  the      on  the   contrary,  are  obedient 

foetal  developing  cell  from  the  stomach  of  a 
pig ;  6,  a  somewhat  more  advanced  cell ;  c-A, 
various  forms  of  the  contractile  fibre-cells 
from  the  mature  body  ;  i,  bundle  of  smooth 
muscle  ;  t,  transverse  section  of  the  latter. 


in  their  rapid  contraction  to 
the  impulses  of  the  will.  But 
the  heart,  a  transversely  striated 

muscle,  also  contracts  involuntarily  like  the  smooth  tissue,  but 

rapidly. 


MUSCLES   AND    NEKVES. 


313 


The  examination  of  smooth  muscles  (fig.  147)  is  in  general 
difficult. 

This  very  tissue  shows  how  important  the  employment  of  suit- 
able reagents  is  for  the  recognition  of  many  textural  conditions. 

For  a  long  time  histologists  regarded  the  elements  of  the 
smooth  muscles  as  flat  bands  (i)  containing  nuclei  placed  behind 
each  other,  and,  in  fact,  the  older  methods  of  investigation 
yielded  nothing  further.  It  was  not  till  about  1847  that  the 
piercing  eye  of  Kolliker  succeeded  in  resolving  these  bands  into 
long  spindle-shaped  cells  arranged  in  rows,  with  a  columnar- 
shaped  nucleus  (c-h).  Since  that  time  the  elements  of  the 
smooth  muscles  bear  the  name  of  contractile  fibre-cells. 

Formerly  acetic  acid  was  generally  used  in  studying  the 
smooth  muscles.     Boiling  the  tissues  (Henle), 
or  hardening  them  in  alcohol,  also  affords  ser- 
viceable preparations,  especially  with  subse- 
quent tingeing  with  carmine. 

More  recently,  however,  we  have  become  ac- 
quainted with  more  conservative  methods. 

For  the  first  examination  the  frog  may 
be  selected,  the  urinary  bladder  and  lungs  of 
which  afford  good  objects  ;  the  smaller  arteries 
of  the  frog  are  also  to  be  recommended.  To 
isolate  single  fibres  without  reagents,  take  the 
walls  of  the  intestines. 

The  more  minute  arrangement  is  to  be  ex- 
amined either  with  the  addition  of  an  in- 
different fluid,  such  as  blood-  and  iodine-serum, 
or  by  the  application  of  reagents.  Impreg- 
nation with  gold  (0.1  per  cent.)  may  be  used, 
but  decidedly  more  may  be  accomplished  by 
macerating  for  one  or  two  days  in  a  very  weak  chromic  acid 
solution  of  0.01-0.05  per  cent. 

The  two  last-mentioned  methods  also  show  us  the  nucleolus 
(fig.  148)  single  or  multiple  (Frankenhauser,  Arnold,  Schwalbe). 
It  was  formerly  overlooked  in  the  tissue  which  was  altered  by 
acetic  acid.  The  nucleolus  is  occasionally  remarkable,  how- 
ever, even  in  the  fresh  cell. 


Fig.  148.  Elements 
of  the  smooth  musclea 
of  the  rabbit. 


314:  SECTION    FIFTEENTH. 

Impregnation  with  silver  is  also  well  adapted  for  the  recog- 
nition of  delicate  strata  of  organic  muscles  ;  for  example,  in  the 
villi  and  the  mucous  membrane  of  the  small  intestine  (His) ; 
likewise  chloride  of  palladium  (F.  E.  Schulze)  and  picric  acid 
(Schwarz),  which  color  yellow. 

Drying,  and  thereupon  tingeing  with  carmine,  and  the  action 
of  acetic  acid,  were  formerly  employed  for  obtaining  transverse 
sections  of  bundles  of  smooth  muscles.  The  preparatory  hard- 
ening by  means  of  alcohol,  chromic  acid,  or  bichromate  oi  potash, 
appears  to  be  more  suitable.  The  most  conservative  treatment 
consists,  however,  in  the  freezing  method,  with  a  subsequent  addi- 
tion of  serum  (Arnold),  or  of  a  0.5  per  cent,  solution  of  common 
salt  (Schwalbe).  For  this  purpose  select  the  walls  of  the  stomach 
or  intestines  of  a  frog  or  mammalial  animal;  the  urinary  blad- 
der of  a  dog  (Schwalbe),  or  a  section  may  be  made  in  a  vertical 
direction  through  the  coats  of  a  larger  artery.  The  two  umbil- 
ical arteries  also  afford  handsome  specimens  by  this  method. 
Thus  (fig.  147  k)  the  transverse  sections  of  the  fibre-cells  will 
be  seen,  some  more  round,  some  more  polyhedral  in  shape,  and 
in  many  of  them  the  transverse  section  of  the  nuclei  may  also 
be  recognized,  and  one  will  be  readily  convinced  that  the  con- 
tractile fibre-cells  are  by  no  means  flattened  structures,  but 
rather  spindle-shaped. 

For  isolating  the  cells  we  have  three  especially  good  methods 
at  present  in  use. 

1.  The  maceration  in  nitric  acid  of  20  per  cent.,  with  which 
Keichert  and  Paulsen  have   made  us  acquainted.     The  first 
effect  is  to  render  the  tissue  darker  and  more  yellow  ;  after  24 
hours  the  separation  of  the  bundles  into  contractile  fibre-cells 
commences,  and  after  three  days  the  latter  readily  fall  apart, 
especially  with  a  little  shaking.     At  the  same  time  a  peculiar 
transversely  wrinkled  or  folded  appearance  occurs  in  the  ele- 
ments of  the  smooth  muscles. 

Muriatic  acid  of  20  per  cent,  also  exerts  a  similar  effect. 

2.  Diluted  acetic  acid. 

This  has  at  all  times  played  an  important  role  in  the  exami- 
nation of  the  tissue  with  which  we  are  at  present  occupied,  and 
was  also  extensively  made  use  of  by  Kolliker  in  his  investiga- 


MUSCLES    AND    NEKVES. 


315 


.a 


tions.  Its  value  lies,  firstly,  as  we  have  already  remarked,  in 
the  rapidity  with  which  it  renders  the  so  characteristic  nuclear 
formation  visible  ;  then,  by  making  the  connective  tissue  trans- 
parent, it  causes  the  bundles  of  smooth  muscles  themselves 
to  become  prominent.  Solutions  of  2-5  per  cent,  are  to  be 
used. 

3.  Treatment  with  30-35  per  cent,  solutions  of  potash. 

If  the  demonstration  of  the  nucleus  be  renounced,  the  solu- 
tions of  potash  of  the  strength  mentioned,  or  one  of  32.5  per 
cent.,  constitute  the  best  means  of  isolating  and  demonstrating 
the  contractile  fibre-cells.  After  an  action  of  15,  20-30 
minutes,  numerous  examples  of  the  latter  may  be  obtained, 
which  are  frequently  of  an  undulating,  serpentine  form. 

The  maceration  in  iodine- 
serum,  or  the  already  mentioned 
extremely  diluted  chromic  acid, 
also  leads  to  the  isolation  of  the 
muscular  elements. 

The  destruction  of  smooth 
muscular  tissue  by  fatty  degen- 
eration of  the  cells  is  a  not  in- 
frequent event,  as  a  normal  oc- 
currence (uterus)  as  well  as  a 
pathological  one ;  likewise  the 
new  formation  of  the  tissue 
from  the  pre-existing.  The  lat- 
ter phenomenon,  however,  re- 
quires a  more  careful  study. 

The  transversely  striated  mus- 
cles (fig.  149)  offer  much  more 
remunerative  objects.  The  more 
important  elements  make  their 
appearance  readily  and  beauti- 
fully, and  only  the  resolution  of 
certain  very  delicate  textural  con- 
ditions leads  to  a  difficult  domain  lying  at  the  limits  of  our 
present  instruments. 

If  we  desire  to  bring  the  fibres  of  the  transversely  striated 


Fig.  149.  1.  Transversely  striated  muscu- 
lar fibril  lae  ;  a,  so-called  primitive  fibres ;  6 
and  c,  transverse  and  longitudinal  lines ;  d, 
nuclei.  2.  A  muscular  fibrilla,  the  sarcous 
portion,  6  6,  of  which  is  torn  in  two  and 
shows  the  empty  primitive  sheath  at  a. 


316 


SECTION   FIFTEENTH. 


muscular  tissue  to  view,  in  as  unaltered  a  form  as  possible,  the 
frog  is  to  be  especially  recommended.  The  animal  is  to  be  de- 
capitated, and  the  well-known  cutaneous  thoracic  muscle,  or  one 
of  the  flat  muscles  running  from  the  os  hyoides  to  the  lower  jaw, 
immediately  cut  out,  avoiding  all  straining  and  tearing.  These, 
with  the  addition  of  blood-serum  or  some  other  indifferent 
fluid,  will  afford  us  excellent  views  of  the  familiar  longitudinally 
and  transversely  striated  fibrillse  (compare  figs.  149,  1 ;  150,  6). 
"We  obtain  similar  appearances  in  the  living  creature  bv  select- 


Fig.  150.  1,  Muscular  filament  with  so-called  primitive  fibrillas  and  distinct  transverse  lines ;  2, 
isolated  fibrillae  more  strongly  magnified;  3,  the  sarcous  portions  united  as  a  disk;  4,  the 
commencing  separation  of  the  disks ;  5,  muscular  filament  after  longer  maceration  in  muriatic 
acid ;  a  and  6,  nuclei ;  c  and  d,  brighter  and  darker  zones ;  6,  two  pointed  fibrillae  of  the  biceps 
brachii,  already  ending  ia  the  course  of  the  muscle. 

ing  the  tail  of  the  frog's  larva  ;  young  fishes  just  hatched  also 
afford  admirable  objects.  If  entire  freshness  be  disregarded,  a 
muscular  fasciculus  from  the  body  of  any  vertebrate  animal 
may  be  used  several  hours  after  death.  A  small  portion  of 
tissue,  carefully  picked  apart  with  needles,  always  affords  good 


MUSCLES    AND    NERVES. 


317 


specimens,  and  shows  us  the  fibrillse  varying  in  their  diameters 
and  markings. 

To  recognize  the  nuclei,  use  a  weak  acid  (diluted  acetic  acid, 
muriatic  acid  of  0.1  per  cent.,  etc.).  They  will  then  be  dis- 
covered in  the  form  of  oval  bodies  (figs.  149,  1,  d\  151,  c).  A 
remainder  of  original  cell-substance  (protoplasma)  surrounds 
the  nucleus  and  extends  beyond  both  its  poles  in  a  spindle- 
shaped  prolongation  (muscle  corpuscles). 

We  do  not  see  the  sarcolemma,  or  the  primitive  sheath  of  the 
muscular  filament  in  the  ordinary  method  of  examination,  as 
this  envelope  closely  surrounds  the 
contractile  contents.  One  may  suc- 
ceed in  recognizing  them  in  various 
ways.  The  muscles  of  the  pisci- 
form  amphibiae,  the  proteus  and 
axolotl,  which  have  been  in  alcohol 
for  some  time,  afford,  without  fur- 
ther preparation,  a  very  good  view 
of  the  loose  and  expanded  envelope. 
If  the  greater  portion  of  the  various 
albuminous  substances  are  dissolved 
by  a  longer-continued  maceration  in 
0.1  per  cent,  muriatic  acid,  one  may 
perceive  the  softened  contents  pro- 
jecting from  a  surrounding  sheath 
at  the  divided  extremities  of  the 
muscular  fibres.  The  sarcolemma 
may  be  completely  isolated,  as 
Kuhne  has  taught  us,  by  means  of 
a  somewhat  complicated  process. 
For  this  purpose  the  muscular  fas- 
ciculus of  the  frog  is  to  be  macerated 
for  a  day  in  water  with  0.01  per 
cent,  of  sulphuric  acid  of  1.83  sp.  wt,  and  then  freed  from  its 
connective  tissue  by  digestion  in  water  at  35-40°  C.,  which 
likewise  requires  24  hours.  The  fibre  is  now  to  be  exposed  for 
a  day  to  the  action  of  muriatic  acid  of  0.1  per  cent. 

However,  we  possess  still  other  accessories,  by  means  of  which 


Fig.  151.  A  muscular  fasciculus  of 
the  frog  by  800-fold  enlargement  a, 
dark  zones  with  sarcous  elements ;  &, 
bright  zones ;  c,  nuclei ;  d,  interstitial 
granules.  (Alcohol  preparation. ) 


318  SECTION    FIFTEENTH. 

we  are  able  to  bring  the  sarcolemma  into  view  instantaneously. 
If  a  bundle  of  muscular  fibres  be  drawn  with  a  pair  of  sharp 
forceps  out  of  one  of  the  muscles  at  the  upper  part  of  the 
thigh  of  a  freshly  decapitated  frog,  one  will  soon  be  able,  by 
the  addition  of  water,  to  recognize  numerous  separations  of  the 
primitive  sheath  from  the  contractile  contents,  as  a  result  of 
the  energetic  imbibition.  At  first  there  are  small,  limpid 
pouches ;  these  soon  grow  larger  and  larger  under  the  eye  of 
the  observer,  neighboring  ones  flow  together,  and  the  vesicular, 
elevated  portions  of  the  sarcolemma  are  separated  by  annular 
constrictions  from  those  which  still  remain  attached. 

Other  muscles  may  also  afford  us  the  desired  result,  if  in 
their  preparation  we  subject  the  several  fibres  to  a  strong  ten- 
sion and  tearing.  In  some  of  them  the  contractile  contents  are 
torn  in  two ;  while  over  this  place  the  more  extensible  sarco- 
lemma remains  intact.  Such  an  appearance  is  seen  in  the  mus- 
cular fibre  fig.  149,  2,  a. 

The  drying  method  served  for  a  long  time  to  show  the  rela- 
tion of  the  several  muscular  fibres  with  each  other,  as  well  as 
the  formation  of  the  bundles  of  muscles  and  of  the  entire  mus- 
cle. Thin  sections  which  were  again  softened,  and  especially 
such  as  were  soaked  in  an  ammoniacal  solution  of  carmine,  and 
subsequently  treated  for  a  few  minutes  with  very  dilute  acetic 
acid,  then  presented  the  frequently  mentioned  and  characteris- 
tic appearance  of  fig.  152  a.  One  may  recognize,  at  the  same 
time,  in  the  muscles  of  man  and  the  mammalian  animals,  the 
manner  in  which  the  nuclear  formation  is  imbedded  in  the  peri- 
phery of  the  contractile  substance,  and  lying  against  the  inner 
surface  of  the  primitive  sheath  (e).  In  the  muscular  fibres  of 
the  heart,  on  the  contrary,  nuclei  also  occur  in  the  more  central 
parts,  a  condition  which  seems  to  predominate  in  the  lower 
vertebrated  animals. 

The  freezing  method  presents  very  much  better  results,  how- 
ever (Cohnheim).  By  the  aid  of  the  highest  magnifying  powers 
one  may  then  recognize  groups  of  sarcous  elements  as  a  mosaic 
of  small,  dull  areolations  of  various  forms  (fig.  153  #),  and  sur- 
rounding these  groups  a  lattice-work  of  transparent  glistening 
lines  (c). 


MUSCLES    AND    NEKVES. 


319 


To  demonstrate  the  branched  muscular  fibres,  as  they  occur 
in  the  heart  and  tongue,  a  30-35  per  cent,  solution  of  potash 
may  be  used  for  the  former  organ,  while  tongues  are  to  be 
immersed  fresh  in  pyroligneous  acid,  or  they  may  be  exposed  to 
the  action  of  this  reagent  after  hardening  in  alcohol  or  chromic 
acid.  The  value  of  the  pyro-acetic  acid  (or  of  a  dilute  acetic 
acid)  naturally  consists  in  its  property  of  rendering  the  connec- 
tive tissue  transparent. 


Fig.  152.  Transverse  section  through 
a  bundle  of  the  biceps  brachii  of  man. 
a,  the  muscular  fibres;  6,  transverse 
section  of  a  vessel ;  c,  a  fat-cell  lying  in 
a  large  connective-tissue  interstice  ;  d, 
capillaries  cut  across ;  «,  nuclei  of  the 
muscular  fibres. 


Fig.  153.  Transverse 
section  through  a  fro- 
zen muscle  of  the  frog. 
a,  groups  of  sarcous 
elements ;  &,  a  nucleus ; 
c,  transparent  trans- 
verse connecting  me- 
dium (Querbindemittel). 


The  isolation  of  the  muscular  fibres  in  their  entire  length  is 
necessary  for  a  number  of  purposes  of  investigation.  In  this 
way  we  recognize  the  course  of  the  fibres  in  a  muscular  fasci- 
culus, the  divisions  of  the  same  as  phenomena  of  growth,  and 
the  increase  in  the  number  of  fibres  in  the  enlargement  of  the 
muscle,  etc.  We  have  the  choice  of  several  methods  for  this 
purpose. 

1.  The  mixture  of  chlorate  of  potash  and  nitric  acid  may  be 
employed  in  various  degrees  of  concentration.  We  are  in- 
debted to  Kuhne  for  a  suitable  procedure.  The  bottom  of  a 
beaker  is  to  be  covered  with  crystals  of  the  chlorate  of  potash, 
slightly  moistened  with  distilled  water,  and  four  times  the  vol- 
ume of  pure  concentrated  nitric  acid  added.  After  considera- 
ble stirring,  the  fresh  muscle  (of  a  frog)  is  to  be  placed  at  the 


320  SECTION    FIFTEENTH. 

bottom  of  the  vessel  and  buried  beneath  the  crystals  of  potash  by 
means  of  a  glass  rod.  In  about  half  an  hour  the  muscle  is  to  be 
removed  from  the  mixture  and  placed  in  water  in  an  ordinary 
test  tube.  This  is  to  be  strongly  shaken,  and  then,  in  fortunate 
cases,  the  tissue  separates  completely  into  fibrillse.  If  this  sep- 
aration does  not  succeed  the  first  time,  the  muscle  is  to  be 
replaced  in  the  mixture  and  exposed  to  the  same  procedure  at 
intervals  of  five  minutes. 

By  this  means  exquisite  specimens  are  obtained,  and  the  nu- 
clei appear  very  finely  in  the  slightly  browned  sarcous  sub- 
stance. 

The  method  given  by  "Wittich  for  using  this  mixture  is  also 
very  judicious.  That  is,  boiling  in  chlorate  of  potash  and 
nitric  acid  strongly  diluted  with  water  (water  200  ccm.,  nitric 
acid  1  ccm.,  and  chlorate  of  potash,  1  grain). 

2.  The  same  may  be  accomplished  by  maceration  for  twenty- 
four  hours  in  0.01  per  cent,  sulphuric  acid  and  the  subsequent 
treatment  for  one  day  with  warm  water,  as  recommended  above 
(p.  317)  for  the  demonstration  of  the  sarcolemma. 

3.  After  the  example  of  Rollett,  the  muscle  may  be  placed, 
without  any  addition  of  water,  in  a  small  glass  tube  which  may 
be  hermetically  sealed  by  the  heat  of  a  lamp  and  then  warmed 
to  120°-140°  C.  on  a  sand-bath  for  ten  minutes.     The  tube  is 
then  to  be  broken  and  the  muscle  agitated  in  warm  water. 

4.  A  strong,  but  no  longer  fuming  muriatic  acid  (p.  129)  may 
also  be  employed  with  advantage.     After  an  action  of  several 
hours  the  interstitial  connective  tissue  is  likewise  found  to  be 
dissolved. 

5.  Finally,  a  potash  solution  of  about  35  per  cent,  also  forms 
a  very  good  accessory.     A  sometimes  slighter,  sometimes  larger 
portion  of  the  muscular  fibres  will  always  be  found  isolated, 
after  an  action  of  from  fifteen  to  thirty  minutes. 

The  high  value  of  reagents  is  not  more  striking  in  any  ques- 
tion with  regard  to  the  structure  of  muscular  tissue  than  that 
of  the  relation  cf  the  muscular  fibre  to  the  tendon. 

Until  recently  it  could  only  be  stated  as  a  true  expression  of 
what  had  been  observed,  that  there  was  no  boundary  to  be  dis- 
covered between  the  contractile  substance  of  the  fibrillse  (fig. 


MUSCLES    AND    NERVES. 


321 


154  a)  and  the  connective-tissue  fibrous  portion  of  the  tendon 
(£),  whether  the  muscle  be  inserted  into'  the  tendon  in  a  straight 
line  or  at  an  oblique  angle.  It  was  therefore  extremely  proba- 
ble that  the  sarcous  portion,  as  well  as  the  sarcolemma,  were 
continued  directly  into  the  tissue  of  the  tendon.  This  continu- 


Fig.  154.  Two  muscu- 
lar fibrillas  (a)  with  the 
apparent  continuation  in- 
to the  connective-tissue 
bundles  of  the  tendon  (6). 


Fig.  155.  Two  muscular 
flbrillae  (a  6)  after  treatment 
wfth  solution  of  potash.  The 
one  still  in  connection  with 
the  tendon  (c),  the  other  sep- 
arated from  the  same  (d). 


ity  of  the  contractile  substance  and  the  connective  tissue  was 
certainly  somewhat  strange,  and  we  might  say  inconvenient. 

At  the  present  day  we  must  all  admit  the  error,  even  though 
we  formerly  defended  this  theory,  since  Weismann  has  discover- 
ed a  medium  in  the  35  per  cent,  solution  of  potash,  which 
decides  in  a  beautiful  and  certain  manner  the  long- contested 
structural  relation. 

After  10,  20-30  minutes  the  muscular  fasciculus  presents  the 
appearance  shown  in  fig.  155  a,  b.  The  apparent  continuity  has 
disappeared.  The  former,  covered  by  the  sarcolemma,  is  sepa- 
rated by  a  sharp  line  of  demarcation  from  the  tendinous  fasci- 
21 


322 


SECTION    FIFTEENTH. 


ctilus  (<?).  In  many  specimens  they  are  even  seen  disconnected 
from  their  tendons  (d),  especially  when  a  slight  pressure  has 
been  made.  There  is  therefore  no  longer  any  doubt  that  the 
fasciculi  of  the  muscles  and  tendons  are  only  "  cemented "  to- 
gether in  the  firmest  manner.  It  is  this  substance,  this  "  tissue 
cement "  which  the  potash  solution  has  dissolved,  which  holds 
them  together. 

While  it  was  formerly  supposed  that  every  transversely 
striated  fibre  continued  throughout  the  entire  length  of  its 
muscle,  more  recently  numerous  exceptions  to  this  have  been 
observed ;  that  is,  muscular  fibres  which  terminate  in  a  point  or 
some  other  form  at  a  greater  or  lesser  distance  from  the  ten- 
dinous extremity  (Rollett,  Weber,  Ilerzig,  and 
Biesiadecky).  Such  fasciculi  (fig.  150,  6)  have 
their  connection  with  the  tendon,  to  a  certain 
extent,  in  the  interstitial  connective  tissue. 
For  these  investigations,  which  are  easy  to 
make,  fresh  as  well  as  boiled  muscles  may 
be  immersed  for  twenty-four  hours  in  glyce- 
rine, or  the  solution  of  potash  mentioned  may 
be  employed. 

To  see  the  extended  capillary  network  of 
the  muscular  tissue  (fig.  156),  they  should  be 
injected  with  transparent  masses,  with  car- 
mine or  Prussian  blue.  Thin,  flat  muscles 
taken  from  a  frog  which  has  been  drowned  in 
alcohol,  and  placed  on  the  microscopic  slide, 
will  bring  to  view  the  capillary  system  filled 
with  blood  in  the  most  beautiful  manner ;  and 
with  a  little  contraction  of  the  muscular  fibres, 
the  delicate  windings  of  the  capillary  vessels 
may  be  readily  recognized. 

Concerning  the  nerves  of  the  muscles,  ref- 
erence is  to  be  made  to  one  of  the  following 
pages. 

The  structural  conditions  which  have  thus  far  been  mention- 
ed of  the  transversely  striated  muscular  tissue  are  all,  as  we 
have  remarked,  relatively  easy  to  examine,  and,  with  the  requi- 


MUSCLES    AND    NEKVES. 


323 


...a 


site  methods,  they  afford  a  suitable  study  for  the  beginner.     It 
is  otherwise  with  regard  to  the  subtle  question  concerning  the 
constitution  of    the   contractile 
substance  which  they   contain, 
the  "  sarcous  substance." 

The  muscular  fibrilke  (fig.  157, 
1)  show  a  double  marking,  which, 
however,  is  subject  to  considera- 
ble variation  as  to  sharpness  and 
distinctness.  We  recognize,  com- 
ing to  the  surface  of  the  fleshy 
substance,  sometimes  over  a  long 
space,  sometimes  only  for  a  short 
distance,  and  then  disappearing 
in  it,  a  fine  longitudinal  marking 
(c),  extending  throughout  the  en- 
tire thickness  of  the  former ;  and 
secondly,  a  likewise  very  fine, 
transverse  linear  marking  (5), 
which  also  may  be  followed 
through  the  entire  substance  of 
the  muscle.  In  many  fibrillae 
the  latter  is  alone  present;  in 
other  specimens  the  longitudinal 
lines  predominate,  occasionally  to  exclusiveness,  and  fine  bands 
and  fibres  (a)  may  project  from  the  cut  extremities.  It  was 
especially  the  latter  cases  which,  in  former  times,  led  the  micros- 
copists  to  the  acceptation  of  a  further  composition  of  the  mus- 
cular fibrillae  out  of  the  finest  fibres,  the  so-called  "primitive 
fibrillae"  (fig.  150,  1,  2).  The  transverse  lines  were  then  gener- 
ally referred  to  a  knotty  condition  of  these  elementary  fibrillae 
resembling  a  string  of  pearls. 

At  the  present  day  this  theory  still  finds  its  defenders,  and 
even  among  renowned  investigators,  although  the  so  much 
improved  optical  accessories  of  the  period  by  no  means  decide 
in  their  favor. 

In  other  specimens  the  transverse  markings  come  out  sharper 
and  more  distinct  (fig.  158,  6).  If  the  longitudinal  lines  are 


Fig.  157.  1.  Transversely  striated  muscular 
fibrillai ;  rt,  so-called  primitive  fibres ;  6  and 
c,  transverse  and  longitudinal  lines  ;  d,  nu- 
clei. 2,  a  muscular  fibrilla,  the  sarcous  por- 
tion, 6  ft,  of  which  is  torn  in  two,  and  shows 
the  empty  primitive  sheath  at  a. 


324 


SECTION   FIFTEENTH. 


wanting,  one  might  even  here  imagine  that  the  muscular  fas- 
ciculus was  composed  of  disks  or  plates  arranged  over  each 
other  in  layers.  The  appearances  become  still  more  deceptive 
where  the  transverse  lines  stand  farther  apart  than  is  the  rule, 


c-- 


Fig.  158.  1,  Muscular  filament  with  so-called  primitive  fibrillae  and  distinct  transverse  lines ;  2, 
isolated  fibrillse  more  strongly  magnified;  3,  the  sarcous  portions  united  as  a  disk;  4,  the 
commencing  separation  of  the  disks ;  5,  muscular  filament  after  longer  maceration  in  muriatic 
acid ;  a  and  ft,  nuclei ;  c  and  d,  brighter  and  darker  zones ;  6,  two  pointed  fibrillae  of  the  biceps 
brachii,  already  ending  in  the  course  of  the  muscle. 

and  where  the  border  or  periphery  of  the  fibrilla  has  inden- 
tations corresponding  to  the  striations. 

The  theory  originated  by  the  English  histologist  Bowman, 
and  further  improved  by  some  of  his  countrymen,  finds  at 
present  the  most  adherents.  According  to  it,  the  contents  of 
the  muscular  fasciculi  consist  of  small  molecular  corpuscles,  the 
so-called  fleshy  particles  or  "  sarcous  elements,"  which  are  held 
together  by  a  homogeneous  connecting  medium,  which  is  in 
reality  twofold,  and  not  exactly  alike  chemically.  According, 
now,  as  the  one  or  the  other  of  these  two  connecting  media  pre- 
dominates, we  see  the  sarcous  elements  united  either  longitudi- 


MUSCLES    AND   NERVES.  325 

nally  or  laterally  ;  in  the  first  case,  the  appearance  of  fibrillse 
(1,  2)  results  ;  in  the  latter,  that  of  transverse  lines  (1)  increas- 
ing to  transverse  plates  (4,  5). 

The  sarcous  elements  in  the  muscular  fibres  of  man  and  the 
mammalia  are  entirely  too  small  to  enable  us  to  state  anything 
with  certainty  in  regard  to  their  form,  although  by  the  use  of 
very  strong  magnifying  powers  they  may  be  shown  with  satis- 


Fig.  159.  Two  muscular  fibrillse,  from  the  proteus,  1,  and  the  hog,  2,  magnified  1000  times  (the 
first  from  an  aicohol  preparation,  the  latter  treated  with  acetic  acid  of  0.01  per  cent.),  a,  sarcoua 
elements ;  b  bright  longitudinal  connecting  medium.  At  a*  the  sarcous  elements  are  further 
apart,  and  the  transverse  connecting  medium  is  visible,  c,  nucleus. 

factory  distinctness  (fig.  159,  2,  a  a*).  The  muscles  of  the  lam- 
prey and  of  the  pisciform  amphibise,  on  the  contrary,  have 
prismatic  sarcous  elements  of  considerable  size,  so  that  in 
alcoholic  specimens  of  the  proteus  (fig.  159,  1)  the  recognition 
of  these  prisms  (a)  0.00075"'  in  size,  and  of  the  more  transpa- 
rent longitudinal  connecting  medium  (U)  becomes  very  easy. 
Furthermore,  the  muscles  of  the  house-fly  form  very  beautiful 
objects ;  their  prismatic  sarcous  elements  distinctly  assume  an 
oblique  position  during  contraction  (Amici).  Similar  sarcous 
elements  are  frequently  to  be  met  with  in  insects ;  their  mean 
longitudinal  diameter  may  be  assumed  to  be  about  0.0015'" 
(Schonn).  The  crab  was  also  very  properly  recommended  for 
this  observation  years  ago  (Hackel),  as  may  be  proved  by  any 
one  who  has  one  of  Hartnack's  immersion  systems,  No.  10  or  11. 
Without  mentioning  that  the  various  appearances  of  the  mus- 
cular fibrillss  may  be  readily  explained  by  what  has  been 
stated,  this  theory  has  received  still  further  important  supports, 
partly  chemical,  partly  optical  in  their  nature,  through  the 
labors  of  German  investigators. 


326  SECTION    FIFTEENTH. 

Firstly,  we  have  a  series  of  reagents  which  attack  the  longi- 
tudinal connecting  medium  more  or  less,  while  the  transverse 
remains  unaltered,  or  is  only  subsequently  affected. 

Yery  dilute  acids  are  here  accorded  the  first  rank.  Thus 
acetic  acid  of  from  0.5-1  per  cent,  causes  in  a  short  time  the 
longitudinal  lines  to  disappear,  and  the  transverse  striations  to 
become  distinct  in  the  swollen  muscular  fibres.  Other  acids, 
as,  for  example,  diluted  phosphoric  acid,  cause  similar  effects. 
The  finest  appearances  are,  however,  afforded  by  the  strongly 
diluted  muriatic  acid  of  0.5,  0.1-0.05  per  cent. 

After  several  hours  one  may  perceive  not  only  the  most  dis- 
tinct transverse  lines  (fig.  158,  5),  but  also  a  regular  breaking-up 
of  the  muscular  fibrillse  into  transverse  disks  (4).  The  same  effect 
is  also  produced  by  the  gastric  juice  by  means  of  its  free  acids. 
Vomited  pieces  of  meat  often  present  similar  extremely  elegant 
appearances.  Older  muriatic  acid  preparations  show  the  mole- 
cular decomposition  more  and  more,  till  at  last  a  mucilaginous 
granular  mass  issues  from  the  opening  in  the  sarcolemma. 

Concentrated  muriatic  acid  causes  the  muscle  to  shrink, 
whereby  sharp  transverse  markings  also,  not  infrequently,  make 
their  appearance. 

However,  not  only  solutions  of  acids,  but  also  those  of  many 
salts  of  the  alkalies  and  alkaline  earths,  such  as  those  of  the  car- 
bonate of  potash,  the  chloride  of  calcium,  and  the  chloride  of 
barium,  present  excellent  media  for  rendering  transverse  plates 
visible  in  most  shrinking  muscular  fibres.  The  transverse  lines 
are  gradually  rendered  very  sharp,  and  there  is  frequently  a 
distinct  breaking-up  into  transverse  plates,  especially  from  the 
action  of  the  carbonate  of  potash. 

On  the  other  hand,  we  have  become  acquainted  with  a  series 
of  other  reagents  which  first  attack  the  transverse  connecting 
medium  of  the  sarcous  elements,  then  dissolve  it,  and  are  thus 
capable  of  producing  the  separation  of  the  muscular  filament 
into  the  so-called  primitive  fibrillse. 

Among  these  may  be  enumerated  the  maceration  of  the 
muscle  in  cold  water,  the  boiling  in  the  same,  an  immersion 
in  absolute  alcohol,  in  diluted  alcohol,  in  diluted  solutions  of 
chloride  of  mercury,  chromic  acid,  and  chromate  of  potash. 


MUSCLES    AND    NERVES. 


327 


The  latter,  after  acting  for  about  a  day,  may  in  favorable  cases 
produce  appearances  such  as  are  represented  in  fig.  160  ;  the 
muscular    filament    becomes    separated,  like    a 
string,  into  long  crooked  threads. 

If  such  a  fibre  be  examined  with  very  strong 
objectives,  one  may  distinctly  recognize  that  it 
is  composed  of  alternating  darker  and  brighter 
zones  (the  sarcous  elements  and  the  longitudinal 
connecting  medium).  Frequently  a  delicate 
transverse  line  may  also  be  seen  passing  through 
the  middle  of  the  more  transparent  intervening 
substance ;  probably  the  place  where,  in  the 
division  of  the  plates,  the  longitudinal  connect- 
ing substance  usually  separates. 

We  cannot  omit  to  mention  that  investiga- 
tions have  lately  been  made  public  by  Krause 
and  Hensen,  which  are  said  to  prove  a  further 
more  complicated  composition  of  the  transversely 
striated  muscular  fibre.  The  object  and  narrow 
limits  of  our  book  do  not  allow  us  to  enter  into 
this  domain,  which  is  at  present  so  obscure. 

The  various  substances  of  the  muscular  fibre  are  still  further 
distinguished,  as  Brucke  ascertained,  by  dissimilar  optical 
properties.  The  substance  of  the  sarcous  elements  consists  of 
a  double  refracting  material,  while  the  longitudinal  connecting 
medium  only  refracts  simply.  Even  with  crossed  nicols,  one 
may  recognize  the  bright  and  dark  zones  interchanging  in 
a  beautiful  manner;  still  finer  appearances  are  produced  by 
the  intercalation  of  a  selenite  or  mica  plate.  According  to  the 
observations  of  this  scientist,  the  muscular  fibre  is  positively 
uniaxal,  and  the  optical  axis  coincides  with  the  long  axis  of  the 
image.  The  muscles  of  insects,  deprived  of  their  water  by 
means  of  alcohol,  and  mounted  in  Canada  balsam,  may  be  em- 
ployed for  these  investigations,  the  correct  interpretation  of 
which  has  since  been  questioned  by  Yalentin  and  Kouget. 
Smooth  muscles  consist,  according  to  Yalentin,  of  a  doubly  re- 
fracting substance. 

The  changes  which  occur  in  the  transversely  striated  muscle 


Pig.  1(50.  Amus 
cular  filament  af- 
ter treatment  for 
twenty-four  hours 
with  chromate  of 
potash. 


328 


SECTION   FIFTEENTH. 


during  its  contraction,  as  well  as  those  which  take  place  after 
death  during  the  rigor  mortis,  deserve  a  more  accurate  study 
with  the  aid  of  our  improved  optical  accessories.  A  few  com- 
munications have  recently  been  made  concerning  the  contrac- 
tion of  the  smooth  tissue. 

The  larva  of  frogs,  or  the  embryos  of  the  hen  or  of  the 
mammalise,  may  be  used  either  fresh  or  hardened  in  alcohol  or 
chromic  acid,  for  the  study  of  the  foetal  muscles  and  of  their 
manner  of  origin.  The  methods  of  investigation  consist  in  the 
preparation  of  fine  sections,  tearing  with  needles,  tingeing  (gly- 
cerine-carmine, hsematoxyline),  and  the  application  of  weak 
acids. 

Fatty  degenerated  muscles  and  those  streaked  with  fat  are  to 
be  examined  either  fresh  or  from  chromic  acid  preparations. 
The  latter,  in  which  the  connective  tissue  between  the  muscular 
fibres  is  changed  into  fat  tissue,  that  is,  into  a  series  of  fat-cells 


a 


Fig.  161.  Human  mus- 
cle streaked  with  fat-cells. 
«,  muscular  fibres ;  &,  rows 
of  fat  cells. 


Fig.  Ifi2.  Fatty  de- 
generated  human 
muscular  fibres,  a, 
Blighter;  6,  increased ; 
c,  highest  degree. 


condition  which  also  occurs  with  high  degrees  of  obesity 
and  over-feeding — is  shown  in  our  fig.  161.  Fig.  162  repre- 
sents the  former  condition,  in  which  fat  molecules  are  formed 
within  the  sarcolemma  at  the  expense  of  the  sarcous  elements, 
\diich  undergo  fatty  degeneration. 


MUSCLES   AND   NERVES.  329 

The  inflammatory  changes  of  the  muscles,  with  their  increase 
of  cells  and  the  typhous  transformations  so  beautifully  de- 
scribed by  Zenker  a  number  of  years  ago,  also  require  similar 
methods  of  treatment. 

We  should  render  ourselves  responsible  for  a  defect  if  we 
should  pass  over  in  silence  a  subject  which  has  recently  awak- 
ened the  greatest  interest  among  physicians  and  laymen ;  we 
refer  to  the  occurrence  of  trichinae  in  the  transversely  striated 
muscular  tissue. 

The  trichina  spiralis,  these  small  forms  of  nematodes,  are,  as 
is  well  known,  eaten  with  the  flesh  of  the  hog  and,  after  a  few 
days,  they  arrive  at  a  condition  of  sexual  ripeness  in  the  human 
intestinal  canal,  so  that  we  now  meet  with  examples  of  some- 
what larger  females  (measuring  more  than  V")  and  smaller 
males  (intestinal  trichinae).  About  a  week  after  the  transplanta- 
tion they  produce  a  multitude  of  very  small  living  young  ones, 
which,  after  perforating  the  walls  of  the  intestines,  find  their 
way  into  the  muscles.  Here  they  force  themselves  through  the 
sarcolemma  into  the  fibres  of  this  tissue,  in  which  they  increase 
considerably  in  size,  so  that  they  may  obtain  a  longitudinal  di- 
mension of  from  -J  to  -J-'"  (muscular  trichinae). 

All  the  transversely  striated  muscles,  with  the  exception  of 
the  heart,  serve  as  a  location  for  these  small  parasites,  whose 
number   may  not   unfrequently  become  extraordinarily  large, 
in  consequence  of  repeated  immigrations. 
Nevertheless,  the -muscles  of  the  jaw  and  f;  ^ 

neck  and  the  diaphragm  are  distinguished  as          /", 

favorite  localities.     The  tendinous  extrem-    i m 

ity  of  the  muscles  —  obviously  because 
there  is  here  a  mechanical  impediment  to 
further  emigration  —  usually  shows  the 
greatest  abundance  of  the  dangerous  guests. 

The  little  worm  devours  a  portion  of  the 
fleshy  mass  beneath  the  sarcolemma  of  the 
muscular  fibre,  where  it  gradually  rolls  fibres;  »,  capsule;  c,  worm, 
itself  up  in  a  spiral  manner.  Around  this  a  capsule  (fig.  163) 
is  gradually  formed,  which  requires  months  for  its  completion. 

While  this  is  taking  place,  we  see  the  muscular  corpuscles  of 


330  SECTION    FIFTEENTH. 

the  neighborhood  increasing  luxuriously  and  forming  a  more 
compact  internal  investing  layer,  to  which  the  thickening  sar- 
colemma  is  also  associated  as  an  external  layer.  The  form  and 
size  of  the  capsules  vary ;  we  meet  with  oval  (more  rarely  cask- 
shaped),  spindle,  and  lemon  shaped  forms,  generally  with  consid- 
erably thickened  extremities.  The  length  is  usually  0.2,  0.3, 
0.5'".  The  calcification  of  the  capsule,  which  commences  in 
the  internal  portions,  begins  late  (scarcely  before  the  expiration 
of  a  year).  This  process,  with  its  further  development,  renders 
the  whole  thing  visible  to  the  unaided  eye  as  a  white  point, 
which  was  not  the  case  with  its  earlier  phases.  The  trichinse 
were  first  discovered  many  years  ago,  in  just  this  latter  con- 
dition, in  which  the  parasite  may  preserve  its  extremely 
tenacious  life  for  many  years  in  the  calcified  capsule. 

The  examination  of  muscles  infected  with  trichinae  is  very 
easy.  Thin  sections  made  in  the  direction  of  the  fibres,  with  or 
without  picking  apart,  will  show  the  presence  of  the  worms 
when  examined  in  the  ordinary  fluid  media,  with  the  addition 
of  acetic  acid  or  alkalies.  A  magnifying  power  of  about  4:0 
diameters  suffices  for  the  first  examination  ;  for  more  accurate 
investigation  one  of  150  or  200  should  be  used.*  In  invalids, 
where  trichiniasis  is  suspected,  fragments  of  muscle  may  be 
removed  from  the  body  with  a  small  harpoon-shaped  instru- 
ment. For  the  microscopical  examination  of  the  flesh  of  the 
hog,  a  number  of  very  thin,  as  large  as  possible  sections  should 
be  taken  from  the  muscles  of  various  parts  of  the  body,  but 
especially  from  the  chief  localities  of  the  parasites. 

Only  injected  muscles,  or  those  intended  for  polarized  light, 
are  to  be  mounted  in  Canada  balsam  for  preservation.  The 
other  preparations  require  to  be  put  up  in  a  moist  condition, 

*  This  object  may  be  accomplished  with  ordinary  and  therefore  cheaper 
microscopes,  with  which  the  several  enlargements  mentioned  in  the  text  may 
be  obtained.  With  this  optical  apparatus,  the  weaker  power  should  show 
distinctly  the  larger  scales  of  the  lepisma  saccharinum  (p.  63  ),  while  the 
stronger  combination  should  afford  a  satisfactory  image  of  the  smaller  forms 
of  the  scales  of  this  insect,  with  their  longitudinal  and  oblique  lines.  Some  of 
the  modern  "  trichina  microscopes  "  fulfil  these  requirements  in  a  satisfactory 
manner,  but  a  quantity  of  the  most  miserable  trash  has  also  been  put  in 
circulation. 


MUSCLES    AND    NERVES.  331 

for  which  purpose  glycerine  diluted  with  water  stands  in  tho 
first  line  ;  in  this  tissues,  especially  those  tinged  with  carmine, 
keep  for  years  in  a  beautiful  manner. 

The  elements  of  the  nervous  system  are  marked  by  exceed- 
ingly variable  qualities,  so  that  in  their  investigation  numerous 
precautionary  measures  become  necessary. 

We  distinguish,  as  is  taught  by  every  hand-book,  white  and 
gray  substance.  The  former  consists  exclusively  of  one  of  the 
two  elements  of  tubes  or  fibres,  called  nerve-tubes,  nerve-fibres, 
primitive  fibres  of  the  nervous  system.  In  the  gray  substance 
we  meet  with  the  second  element,  together  with  a  sometimes 
slighter,  sometimes  greater  quantity  of  the  nerve-fibres.  This 
second  element,  the  ganglion-body,  ganglion-cell,  or  nerve-cell, 
is  generally  a  large  cellular  structure  with  a  vesicular-shaped 
nucleus.  The  other  constituents  consist  of  connective  substance 
in  various  stages  of  development,  and  blood-vessels. 

In  order  to  see  the  nerve-tubes,  which  consist  of  an  albumi- 
nous central  fibre,  the  so-called  axis  cylinder ;  of  a  peculiar  sub- 
stance surrounding  this,  the  nerve-medulla  or  the  medullary 
sheath ;  and  of  a  very  fine  envelope  surrounding  the  whole  and 
holding  it  together,  the  primitive  sheath  or  the  sheath  of 
Schwann,  in  as  unaltered  a  condition  as  possible,  we  cannot 
proceed  too  rapidly,  and  must,  at  the  same  time,  avoid  almost 
all  preparatory  manipulation.  For  this  reason,  there  are  but 
few  parts  of  the  bodies  of  vertebrated  animals  which  afford 
suitable  objects.  The  cornea  of  a  small  mammalial  animal  just 
killed,  for  example,  that  of  a  rabbit  or  of  a  mouse,  may  be  ex- 
amined on  the  warm  stage  without  the  addition  of  any  fluid 
medium.  The  cornea  should  be  incised  at  its  margin.  A  very 
fine  form  of  nerve-fibres  will  here  be  met  with.  The  frog 
affords  better  preparations  ;  its  transparent  eyelid  shows  larger 
tubes,  isolated  or  lying  together  in  bundles.  The  tails  of  their 
larvae  permit  the  observation  to  be  made  on  the  living  creature. 

Quite  fresh,  unaltered  nerve-fibres  should  present  the  appear- 
ance of  entirely  homogeneous,  opaline,  cylindrical  fibres,  in 
which  there  is  no  trace  of  any  further  composition  to  be  recog- 
nized. The  addition  of  iodine  serum  is  here  to  be  recom- 
mended. 


332 


SECTION   FIFTEENTH. 


If  we  take  a  nerve  from  the  body  of  an  animal  recently 
killed,  and  pick  it  in  water  with  needles,  notwithstanding  the 
greatest  rapidity  of  manipulation,  it  is  no 
longer  possible  to  obtain  the  natural  con- 
dition ;  on  the  contrary,  its  appearance 
is  more  or  less  changed  ;  there  is  an  alter- 
ation of  the  medullary  sheath  which  it 
has  been  agreed  to  call  a  coagulation. 

Our  fig.  164  may  represent  the  com- 
mencement of  this  coagulation.  In  the 
beginning  it  gives  the  nerve-fibre  a  darker 
contour.  Soon,  however,  we  see  a  thin 
peripheral  layer  coagulated  and  separated 
by  a  second,  more  internal  and  finer  line 
from  the  central  portion  of  the  medulla, 
which  is  not,  as  yet,  drawn  within  the 
sphere  of  these  changes.  But  to  present 
these  "  double  contours  "  the  nerve-tubes 
must  have  a  certain  thickness  (a  &).  If 
the  transverse  diameter  falls  below  a  cer- 
tain size,  the  tubes  then  and  afterwards 
appear  with  only  simple  contours  (c  d  e\  but  at  the  same  time 
they  readily  assume  a  peculiar  appearance, — they  become  "  vari- 
cose," as  it  is  called. 

Further  changes  render  the  coagulated  peripheral  layer 
broader,  and  frequently  show  an  irregularity  of  the  inner  con- 
tours. The  process  may  here  become  stationary ;  the  coagu- 
lated portion  protects  the  internal,  still  uncoagulated  medulla 
to  a  certain  extent.  But  generally  this  is  also  drawn  into  the 
sphere  of  the  changes  ;  the  previously  homogeneous  appearance 
is  lost ;  a  few  lumpy  formations  make  their  appearance  in  it 
and  increase  in  number  and  size  ;  not  unf  requently  the  whole 
becomes  a  granular,  crumbling  mass.  But  all  nerve-tubes  do 
not  behave  in  exactly  the  same  way  ;  we  may  meet  with  them 
lying  close  beside  each  other,  showing  various  phases  of  coagu- 
lation. 

We  have  jiot  yet  perceived  anything  of  the  axis-cylinder  and 
the  delicate  envelope. 


a,          6  e 

Fig.  164.  Human  nerve-fi- 
bres, a,  broad  ;  •  6,  medium 
breadth ;  c  d  e,  fine. 


MUSCLES    AND    NERVES.  333 

The  so-called  nerve-medulla  is  a  mixture  of  peculiar  sub- 
stances of  cerebrine  and  lecithine,  with  a  very  changeable  body 
belonging  to  the  albuminous  group.  "We  shall  therefore  un- 
derstand why  reagents,  such  as  strong  alcohol,  concentrated 
chromic  acid,  a  solution  of  corrosive  sublimate,  and  many  others 
which  have  a  coagulating  effect  on  albumen,  should  also 
produce  the  more  advanced  phases  of  coagulation  almost 
instantaneously. 

For  the  same  reason  it  is  unnecessary  to  state  that  such  a 
coagulated  nerve-medulla,  by  the  addition  of  alkaline  solutions, 
such  as  those  of  potash  or  soda,  again  assumes  a  more  fluid  and 
homogeneous  condition,  and  exudes  from  the  cut  ends  of  the 
nerve-tubes  in  the  shape  of  double-contoured,  fat-like  drops 
and  filaments. 

If  strong  pressure  be  made  with  the  covering-glass  on  the 
nerve-tubes,  treated  in  this  manner  with  alkalies,  the  medulla 
may  be  forced  out  of  many  of  them,  and  in  this  way  the  empty, 
homogeneous,  extremely  delicate  primitive  sheath  may  be  seen. 
If  careful  search  be  made  among  the  nerve-fibres,  which  have 
been  isolated  by  picking  a  nerve-trunk  apart,  a  few  will  be 
met  with  in  which  their  contents  have  been  somewhat  displaced, 
in  consequence  of  the  pulling  and  the  pressure  of  the  prepar- 
ing-needle ;  and  the  sheath,  which  is  generally  collapsed,  may 
also  be  recognized  for  a  short  distance. 

It  was  frequently  denied,  at  a  former  epoch,  that  the  axis- 
cylinder  was  an  integral  constituent  of  the  nerve-tubes,  and 
this  was  quite  proper,  for,  with  the  accessories  then  employed, 
it  could  only  be  brought  to  view  in  an  isolated  condition.  At 
the  present  day  it  is  a  small  matter  to  demonstrate  these  fibres 
in  all  nerve-tubes;  and  we  have  the  choice  between  several 
methods. 

For  the  demonstration  of  the  same,  Schulze's  reagent,  the 
mixture  of  chlorate  of  potash  and  nitric  acid  may  be  employed 
(Budge  and  Uechtritz).  Chloroform  renders  good  service  (Wal- 
deyer),  and  collodion  is  very  excellent  (Pfliiger).  A  fresh  nerve 
is  to  be  picked  apart  on  the  slide,  without  any  addition  of  fluid. 
A  large  drop  of  collodion  is  then  to  be  added,  the  covering- 
glass  placed  over  it,  and  the  examination  made  immediately. 


334 


SECTION    FIFTEENTH. 


The  nerve-tubes  rapidly  become  more  and  more  pale,  and, 

instead  of  the  dark  medulla,  only  a 
few  granules  are  to  be  seen  envel- 
oped by  the  distinct  primitive 
sheath.  This  becomes  contracted, 
and  thus  frequently  shows  a  series 
of  extremely  characteristic  invagi- 
nations.  The  axis-cylinder  appears 
in  each  tube  as  a  pale  fibre.  During 
the  contraction  of  the  nerve-fibre  it 
frequently  appears  to  bfe  too  long ; 
and  not  unfrequently,  under  the 
eye  of  the  observer,  it  shoves  itself 
through  the  axis  towards  the  peri- 
phery, and  protrudes  as  a  fibre  from 
the  cut  extremity  (fig.  165  c). 

This  interesting  appearance  may 
be  followed  in  this  manner  for  a 
short  time,  but  it  soon  undergoes 
further  changes,  and  often  becomes 
entirely  unserviceable  in  a  quarter 
of  an  hour. 

I  afterwards  found  in  aniline 
red  of  the  above-mentioned  (p.  156) 
strength  a  new  accessory  for  the  demonstration  of  the  axis- 
cylinder  in  fresh  medullated  tubes.  Frog's  nerves,  picked 
apart  and  placed  in  the  solution,  show  in  from  4  to  12  hours  the 
beautifully  reddened  axis-cylinders  glistening  through  the  fatty 
enveloping  mass. 

Still  other  methods  permit  of  the  recognition  of  the  axis- 
cylinder  in  a  beautiful  manner.  Thus,  after  a  longer  treatment 
with  strong  alcohol  or  ether,  it  may  be  rendered  visible  in  the 
tubes  deprived  in  this  way  of  their  fat.  A  solution  of  subli- 
mate and  Moleschott's  acetic  acid  mixture  also  afford  good 
specimens.  Chromic  acid  preparations  (or  those  obtained  by 
means  of  chromate  of  potash)  present  very  beautiful  appear- 
ances. Long,  hardened  filaments  frequently  project  from  the 
cut  extremities  (bf). 


Fig.  165.  a-c,  nerve-fibres  of  the  frog 
treated  with  absolute  alcohol  (fl),  chro- 
mate of  potash  (6),  and  collodion  (c),  all 
showing  the  axis-cylinder ;  d,  non-me- 
dullated  fibre  from  the  lamprey ;  e, 
non-medullated  nerve-fibres  from  the  ol- 
factory nerve  of  the  calf ;  /.  gr,  A,  nerve- 
tubes  of  a  fine  form  with  axis-cylinders ; 
that  of  g  becomes  at  *  a  branch  of  a 
ganglion-cell. 


MUSCLES    AND    NERVES.  335 

Impregnation  with  various  metals  has  also  been  used  recently 
for  demonstrating  the  axis-cylinder.  Nitrate  of  silver  either 
gives  it  a  uniform  dark  color,  or  causes  it  to  assume  peculiar 
transversely  striated  appearance,  reminding  one  of  muscular 
fibre  (Frommann,  Grandly).  The  chloride  of  gold,  recom- 
mended by  Cohnheim  (if  successfully  employed),  shows  the 
axis-cylinder  shining  bright-red  through  the  dark-red  medullary 
substance ;  it  afterwards  appears  blackened.  Osmic  acid,  on 
the  contrary,  very  soon  blackens  the  nerve-medulla,  while  the 
axis-cylinder  remains  colorless  or  only  slightly  browned  (M. 
Schultze),  so  that  we  possess  in  our  reagent  an  excellent  acces- 
sory for  deciding  the  presence  or  absence  of  the  medullary 
sheath  of  the  peripheral  ramifications  of  the  nerves. 

We  have  finally  to  mention  the  recognition  of  the  axis-cylin- 
der in  transverse  sections  of  previously  hardened  nerve-trunks  ; 
this  is  also  of  particular  interest  in  still  another  regard.  If  a 
human  or  mammalial  nerve  be  immersed  for  a  short  time,  first 
in  chromic  acid  solution  of  0.2,  then  in  one  of  0.5  per  cent.,  it 
will  attain  such  a  consistence  as  to  permit  the  finest  trans- 
verse sections  to  be  made  with  a  sharp  razor.  These,  tinged 
with  carmine,  are  to  be  deprived  of  their  water  by  means  of 
absolute  alcohol,  and,  after  soaking  in  turpentine,  mounted  in 
Canada  balsam.  Then,  the  medulla  having  become  transparent, 
the  axis-cylinder  may  be  recognized  as  a  small  reddened  circle, 
surrounded  by  transparent  medulla,  which  forms  a  single  or 
multiple  circle  around  the  axis-cylinder  (a  condition  to  which 
attention  was  called  several  years  ago  by  Lister  and  Turner,  and 
which  it  has  not  as  yet  been  possible  to  explain),  and  finally 
the  whole  is  found  to  be  surrounded  by  the  simple  contour  of 
the  transversely  divided  primitive  sheath. 

Formerly,  the  axis-cylinder  was  generally  regarded  as  a 
homogeneous  structure,  although  there  has  never  been  any  want 
of  manifold  testimony  to  its  more  complicated  formation. 
Newer,  more  conservative  methods  show  that  it  is  with  great 
probability  composed  of  the  finest  fibres,  the  axis  fibrillse  of 
"VValdeyer  or  the  primitive  fibrillse  of  M.  Schultze  (fig.  166). 
The  white  substance  of  the  brain  and  spinal  cord  serves  best 
for  their  recognition  in  medullated  nerve-fibres.  The  fresh 


336 


SECTION    FIFTEENTH. 


object  may  be  examined  in  blood-serum  with  very  strong  mag- 
nifying powers,  but  it  is  preferable  to  macerate  for  a  day  or 
more  in  iodine-serum.  Osmic  acid  (|— J  per  cent.)  renders 


Fig.  166.  Fibrillated  arrange- 
ment of  the  axis-cylinder  after 
Schultze.  o,  a  thick  axis-cyl- 
inder from  the  spinal  cord 
of  the  ox ;  6,  nerve-fibre  from 
the  brain  of  the  torpedo. 


Fig.  167.  Sympathetic 
nerve-branch.  Two  mertul- 
lated  nerve-tubes  (a),  sur- 
rounded by  numerous  fibres 
of  Eemak  (&). 


excellent  service.  After  a  short  action  the  axis  cylinder  be- 
comes sufficiently  hardened  without  any  granular  opacities,  and 
shows  the  longitudinal  markings  very  distinctly,  especially  when 
freed  from  the  medullary  sheath  (Schultze) ;  although  this  sheath 
does  not  form  any  obstacle  to  the  recognition  of  the  axis- 
cylinder. 

Medullated  tubes  are  not  shown  by  all  the  nerve-trunks  in 
man  and  the  mammalia,  however.  The  fibres  of  the  olfactory 
nerve  (fig.  165  e)  all  appear  pale  and  nucleated,  and  by  proper 
treatment  may  be  resolved  into  a  bundle  of  the  finest  primitive 
fibrillse.  In  the  ramifications  of  the  sympathetic  nervous  system 


MUSCLES    AKD    NERVES. 


337 


3f  man  and  the  higher  vertebrata,  there  also  occurs  intermingled 
with  medullated  nerve-tubes  a  system  of  pale,  nucleated  fibres, 
which  bear  the  name  of  Remak's  fibres,  after  their  discoverer, 
Remak  (fig.  167  &).  Considerable  controversy  has  arisen  as  to 
their  nature,  whether  nervous  or  of  connective  tissue ;  but  at 
the  present  time  there  is  no  further  doubt  as  to  their  nervous 
constitution.  Indeed,  in  the  earlier  embryonic  periods,  all 
nerve-tubes  appear  pale,  non-medullated  and  nucleated.  Final- 
ly, in  the  lower  vertebrata,  all  the  nerve-tubes  may  remain 
through  life  at  this  stage  of  development,  as,  for  instance,  in 
the  lamprey,  of  which  such  a  nerve  is  represented  by  our  fig. 
165  d. 

For  .the  examination  of  these  pale,  nucleated  fibres,  the  fresh 
tissue  may  be  employed,  with  picking  and  perhaps  the  addi- 
tion of  a  weak  acid.  A  longer  immersion  in  very  dilute  acetic 
acid  (about  20-50  ccm.  water,  with  a  few  drops  of  hydrated 
acetic  acid)  is  preferable.  A  maceration  in  weak  solutions  of 
chromic  acid  and  of  chromate  of  potash,  of  the  degrees  of  con- 
centration given  by  Schultze  (comp.  above  p.  131),  also  pro- 
duces very  beautiful  specimens.  Chloride  of  palladium  was 
also  recommended  by  Bidder. 
One  of  the  ordinary  tingeing 
methods  may  be  employed  for 
demonstrating  the  nuclei. 

The  examination  of  the  nerve- 
fibres  in  polarized  light  shows  the 
interesting  fact  of  a  double  re- 
fracting positive  sheath,  and  a 
likewise  double  refracting  but 
negative  medulla.  The  long  axis 
of  the  primitive  fibres  and  the 
optical  axis  coincide.  Yalentine, 

tr>  wlinTYi  WP  arp  inrlphfprl  fnr  fhk  Fig.  168.    Ganglion-cells  of  the  mammalia. 

.1  We  are                                             a  ^    cell3  with    connective-tissue  envelopes, 

infoT'ocfinrv     T-ncmlf       rornaWlra     fhaf  from  which  spring  Remak's  fibres  d  d  ;  a,  a 

interesting     reSUit,     remaiKS     tnat  cell  without  a  nucleus  ;&,  two  single  nuclea- 

r.r>  -™-.«      4-V.          -r^VU    -*-Vn-w  nlA  s^-£    4-l-.i->.  ted  ones;  and  c,  one  with  two  nuclei;  B,  a 

We  may  thus,  With   the  aid  O±    the  ganglion '^dy  without  an  envelope. 

polarizing  apparatus,  distinguish 

the  medullated  from  the  non-  medullated  nerve-tubes. 

We'  have  now  to  speak  of  the  examination  of  the  second 

22 


338  SECTION   FIFTEENTH. 

elementary  form  of  the  nervous  system,  the  ganglion  cells 
(Figs.  168, 169.) 

These  appear  as  cells  of  considerable  size,  although  subject 
to  great  variation  in  this  regard,  with  large,  round,  vesicular 
nuclei  and  a  rather  thick,  very  finely  granular,  sometimes 
colorless,  sometimes  pigmented  cell-body,  which  usually  hardens 
into  a  thin  rind  at  its  periphery.  Accessory  envelopes  are 
found  covering  these  ganglion  bodies  in  the  peripheral  gan- 
glia, and  are  either  (as  is  generally  the  case  in  the  lower  ver- 
tebrates) a  homogeneous  membrane  or  a  thicker,  nucleated,  con- 
nective-tissue substance,  which  shows  numerous  nuclei  imbed- 
ded in  it,  and  not  unfrequently  runs  out  into  thread-shaped 
processes  presenting  the  appearance  of  Kemak's  fibres.  • 


Fig.  169.    A  multipolar  ganglion-cell  from  the  gray  substance  of  the  human  brain. 

An  epithelium -like  lining  on  the  inner  surface  of  these 
envelopes  is  of  interest.  Nitrate  of  silver,  or  the  method 
of  impregnating  with  gold  indicated  by  Gerlach  (p.  165),  may 
be  employed  for  demonstrating  the  latter. 

The  first  incomplete  view  of  the  ganglion  bodies  may  be  ob- 
tained either  by  selecting  a  small  ganglion,  for  example,  a 
spinal  ganglion  of  a  frog  or  a  mouse,  and  carefully  picking  it 
apart  with  sharp-pointed  needles,  with,  the  addition  of  an  indif- 
ferent fluid  medium,  or  a  thin  section  from  a  larger  fresh  gan- 
glion may  be  subjected  to  the  same  treatment. 

Naturally,  by  this  procedure,  numerous  divisions  of  the  con- 
nection take  place,  and  the  absence  of  a  sufficient  insight  into 
the  arrangement  of  the  whole  is  felt.  To  obtain  these,  places 
should  be  selected  iu  small  creatures  where  microscopic  gangli- 
onic  swellings  occur  on  fine  nerve-branches,  which  may  be 


MUSCLES    AND    NERVES.  339 

viewed  in  their  totality  without  preparatory  manipulation.  For 
this  purpose  the  frog  stands  in  the  first  line.  The  small 
embedded  ganglia,  frequently  consisting  of  only  a  few  cells, 
which  may  be  recognized  on  the  cardiac  nerves  in  the  septum 
of  the  ventricles,  or  on  the  branches  of  the  sympathetic  system, 
afford  admirable  specimens.  Schwalbe  praises  the  spinal  gan- 
glia of  the  lizard.  A  very  dilute  acetic  acid  may  here  be  used 
with  advantage.  Strongly  diluted  phosphoric  acid  has  also 
been  recommended  for  this  purpose ;  likewise  (although  less 
suitable)  very  weak  solutions  of  potash  and  soda  (Schwalbe). 

The  relation  of  the  nerve-fibres  to  the  ganglion  bodies  is  of 
great  importance.  As  is  known,  the  opinions  of  investigators 
have  undergone  great  changes  in  this  regard  of  late  years,  and 
even  at  the  present  time  we  are  far  from  meeting  with  coin- 
ciding or  even  similar  views. 

Although  it  was  at  first  considered  that  there  was  but  a  simple 
juxtaposition  of  both  elementary  forms  in  a  ganglion  (Va- 
lentin), connections  of  the  ganglion-cells  with  the  nerve-tubes 
were  afterwards  frequently  observed  (Wagner,  Robin,  Bidder, 
and  others),  and  the  doctrine  of  bipolar,  multipolar,  unipolar, 
and  apolar  ganglion  cells  founded.  This  is  not  the  place  to 
test  the  correctness  of  these  various  opinions,  and  we  must  refer 
on  this  point  to  the  text-books  on  histology. 

The  se\reral  animal  groups  are  of  very  unequal  service  for 
ascertaining  the  origins  of  such  fibres  by  means  of  picking. 
The  scanty  admixture  of  a  soft,  loose  connective  tissue  with  the 
nervous  elements  of  a  ganglion  f  acifttates  the  acquisition  of  this 
knowledge  very  much.  A  more  plentiful  admixture  of  a 
firmer,  interweaved  connective-tissue  formation  either  renders 
the  isolation  difficult  to  a  high  degree,  or  makes  it  entirely  im- 
possible. The  cartilaginous  fishes  (rays),  therefore,  form  ex- 
tremely favorable  objects  in  the  former  regard,  and  many  osse- 
ous fishes  are,  at  least,  serviceable.  The  bodies  of  the  naked 
amphibise  are  less  suitable,  and  the  ganglia  of  man,  the  mam- 
malia, and  birds  are  scarcely  to  be  mastered  with  the  prepar- 
ing needles. 

Suitable  ganglia,  for  example,  those  of  the  trigeminus,  vagus, 
and  the  spinal  nerves  of  the  pike  and  the  burbot  (Gadus  lota) 


340  SECTION   FIFTEENTH. 

may  be  picked  apart  either  fresh  or,  which  may  not  be  called 
unserviceable,  a  few  hours,  10-15,  after  death.  A  preparatory 
maceration  for  a  day  in  dilute  chromic  acid  (0.1-0.5  per  cent.) 
may  also  be  employed.  We  also  recommend  the  trial  of  a  method 
indicated  by  J.  Arnold,  which  affords  good  results,  at  least  with 
the  frog.  The  ganglion  is  to  be  placed  for  four  or  five  minutes 
in  acetic  acid  of  0.3-0.2  per  cent.,  and  then  for  twelve  to  forty- 
eight  hours  in  a  0.02—0.01  per  cent,  solution  of  chromic  acid. 
The  preparatory  treatment  with  a  very  dilute  solution  of  chlo- 
ride of  gold  (0.005  per  cent.)  has  also  been  used  (Bidder).  Not- 
withstanding every  precaution,  numerous  fractures  and  lacera- 
tions are  unavoidable. 

Hardening  in  chromic  acid  or  in  chromate  of  potash  may 
also  be  used  with  the  higher  vertebrates.  In  such  cases  one 
should  begin  with  weak  solutions  of  the  acid,  of  0.2-0.5  per 


Fig.  170.  A  sympathetic  ganglion  of  a  mammalial  animal.  The  medullated  nerve-tubes  of  the 
three  trunks,  a  b  c,  pass  through  a  profuse,  nucleated  fibrous  tissue  (Remak's)  ;  d,  multipolar  gan- 
glion-cells ;  at  d*,  one  with  a  dividing  nerve-fibre ;  «,  unipolar,  /,  apolar  cells. 


cent.,  change  them  frequently,  and  gradually  increase  the  con- 
centration. The  chromate  of  potash  is  employed  in  correspond- 
ing quantity  (comp.  p.  139).  The  ganglia  thus  hardened  per- 
mit of  very  thin  sections  being  made  with  a  sharp  razor,  which 
are  to  be  examined  in  glycerine  diluted  with  water.  One  will 


MUSCLES    AND    NERVES. 


341 


thus  be  able  to  recognize  appearances,  for  instance,  in  a  sympa- 
thetic ganglion  of  a  mammalial  animal,  which  come  near  to  our 
fig.  170,  which  is  indeed  drawn  somewhat  diagrammatically. 
Multipolar  cells  (d  d)  are,  as  it  seems,  of  very  frequent  occur- 
rence in  the  sympathetic  ganglia  of  the  mammalia,  in  contradis- 
tinction to  those  of  the  lower  vertebrata,  in  which  bipolar  and 
unipolar  constitute  the  rule.  The  ganglion-cells  of  the  sympa- 
thetic of  the  rabbit  and  the  Guinea-pig  appear  to  have  two  nuclei. 

More  recently  we  have  become  acquainted  with  other  suitable 
methods.  These  sections  of  chromic  acid  preparations  may  be 
placed  for  12-24  hours  in  a  solution  of  osmic  acid  (1  per  cent.), 
in  which  the  nerves  become  blackened.  The  solution  of  the 
chloride  of  palladium  (1:500)  is 
still  better,  however,  because  it 
hardens  and  colors  at  the  same 
time.  Even  after  24  hours  (if 
the  fluid  has  been  changed  in  the 
mean  time)  the  ganglion  may  show 
a  blackish-gray  color  and  be 
ready  for  preparation.  If  the 
cut  surface  is  still  yellow,  a 
further  action  till  a  following 
day  is  then  sufficient.  Yery  in- 
structive appearances  result,  as 
the  connective  tissue  is  pale,  the 
ganglion-cells  yellow-brown,  and 
the  nerve -fibres  blackish 
(Schwalbe). 

These  hardened  ganglia  may 
be  examined  in  still  another 
way.  The  sections  are  to  be 
stained,  then  deprived  of  their 
water  by  means  of  absolute 

,  ,  ,  i  .-,  e>  Fig.  171  •  Ganglion-cell  from  the  sympa 

alCOnol.  and  Oil  OI  tUrpeil-  thetic  of  the  hyla  or  green-tree  frog  (after 

.  _  Beale).  a,  cell-body ;  6,  sheath  ;  c,  straight 

tine  added.  It  the  brain  OI  a  nerve-fibre ;  and  d,  spiral  fibre ;  continua- 

;  tion  of  the  former,  e,  and  of  the  latter,  /. 

small    mammal,   a   rabbit,  or   a 

Guinea-pig,  be  thoroughly  injected  from  the  arch  of  the  aorta 

with  carmine  gelatine,  the  Gasserian  ganglion,  after  delicate 


342  SECTION   FIFTEENTH. 

staining  with  carmine,  affords  excellent  specimens  of  this 
kind. 

"Within  a  short  time  another  interesting  structural  condition 
has  been  observed  in  the  ganglion-cells  of  the  sympathetic  of  the 
frog  (fig.  171).  From  the  cell  (a) — and  from  the  central  portion 
of  its  body — arises  a  straight  fibre  (c  e)  (axis-cylinder),  in  which 
a  nuclear  formation  is  not  unfrequently  remarked.  These  are 
surrounded  by  one  or  several  spiral  fibres,  which  likewise  pre- 
sent nuclei  (d).  They  originate  from  the  surface  of  the  cell- 
body. 

This  was  the  condition  which  Beale  found  in  glycerine  pre- 
parations tinged  with  carmine.  Arnold,  an  able  investigator, 
who  made  use  of  the  method*  mentioned  at  p.  340,  states  that 
both  varieties  of  fibres  arise  from  the  nucleolus  of  the  ganglion- 
cell.  I  could  not  convince  myself  of  this,  and  am  inclined  to 
regard  Beale's  spiral  fibre  as  elastic.  Nevertheless,  by  this  the 
possibility  is  not  to  be  denied  that,  in  the  bipolar  ganglion- 
cells,  where  both  nerve-fibres  arise  close  to  each  other,  the  one 
may  surround  the  other  with  convolutions. 

Remarkable  ganglionic  apparatuses  of  microscopical  fineness 
have  recently  been  discovered  in  the  walls  of  the  abdominal 
viscera. 

*  In  a  second  article  the  author  communicates  new  and  more  complicated 
methods  for  the  investigation  of  these  ganglion-cells.  To  isolate  the  spiral 
fibres  in  the  greatest  possible  length,  immerse  them  in  5  com.  of  nitric  acid 
of  from  0.01  to  0.02  per  cent.  Even  after  five  to  ten  minutes  the  structure  of 
the  ganglion-cell  becomes  clear.  After  an  immersion  of  from  twelve  to  twen- 
ty-four hours,  however,  these  fibres  may  be  followed  very  far  into  the  nerve- 
trunk,  and  be  seen  to  become  true  nerve-fibres.  Chloride  of  gold  also  colors 
both  varieties  of  fibres,  the  straight  as  well  as  the  spiral,  Immerse  the  tissue 
in  4-5  com.  of  a  0.02-0.05  per  cent,  mixture  of  1  per  cent,  acetic  acid  and 
chloride  of  gold  and  potassa.  When  the  first  traces  of  a  violet  color  make 
their  appearance  (after  about  three  to  four  hours),  the  main  trunk  of  the  sym- 
pathetic is  to  be  placed  in  10  com.  of  acetic  acid  of  the  above-mentioned 
strength.  The  color  has  become  intense  in  from  four  to  five  days,  and  the 
connective  tissue  remains  light  and  loose.  A  microscopic  preparation,  to 
which  acidulated  glycerine  has  been  added,  is  now  to  be  placed  on  a  white  sur- 
face, and  exposed  to  the  action  of  day  or  sun  light  for  the  further  reduction  of 
the  gold.  After  four  to  five  days  the  straight  nerve-fibre  has  become  bright 
red  ;  the  thickest  of  the  spiral  fibres  also  present  the  same  appearance,  while 
the  finer  ones  only  gain  an  intense  color  on  the  eighth  or  tenth  day. 


MUSCLES   AND    .NERVES.  343 

To  these  belong  the  ganglia  in  the  submucous  connective  tis- 
sue of  the  digestive  apparatus  (fig.  172),  discovered  by  Meissner, 


Fig.  172.   A  ganglion  from,  the  submucous  tissue  of  the  intestinal  canal  of  a  child  ten  days  old 
(pyroacetic  acid  preparation),      a,  ganglion ;  &,  its  radiating  nerve  branches ;  c,  injected  capillary 


network. 


and  then  investigated  by  Remak,  Manz,  Kollmann,  Billroth,  and 
others.  Likewise  the  plexus  myentericus,  pointed  out  by  Auer- 
bach,  a  highly  developed  ganglionic  network  between  the  two 
muscular  layers  of  the  intestinal  canal. 

The  examination  of  these  submucous  nerve-ganglia  has  for 
the  most  part  been  made  with  the  aid  of  maceration  in  pyro- 
acetic acid.  But  many  observers  (Billroth,  for  example)  have 
committed  the  fault  of  allowing  this  reagent  to  act  in  much  too 
energetic  a  manner,  and  were  therefore  able  to  describe  arte- 
factions  only.  Portions  not  too  large,  taken  from  the  fresh 
body,  are  to  be  placed  in  purified  pyroligneous  acid  diluted 
with  one  or  several  times  its  volume  of  water.  After  one,  two, 
or  three  days  the  examination  should  be  attempted  on  vertical 
sections,  or  the  isolated  submucous  tissue  (likewise  surface  sec- 
tions of  the  latter  made  with  the  scissors),  in  order  to  recognize 
the  horizontal  ramifications. 

A  certain  attention  is  always  necessary  in  this  case,  because 
exactly  the  proper  degree  of  maceration  must  be  employed  in 


344  SECTION   FIFTEENTH. 

the  investigation,  and  an  excessive  action  of  the  pyroacetic  acid 
soon  follows.  The  pyroacetic  acid  may  also  be  replaced  with 
very  dilute  acetic  acid.  One  may  also  succeed,  for  example,  in 
the  new-born  child,  in  demonstrating  this  ganglionic  plexus 


Fig.  173,  1.  A  large  ganglion  from  the  email  intestine  of  a  child  10  days  old.  a,  the  ganglion, 
with  the  ganglion  cells;  b  c,  efferent  nerve-branches,  with  "pale  nucleated  fibres  in  a  fresh  condi- 
tion. 2.  Such  a  nerve-trunk  from  a  boy  5  years  old,  with  three  pale  primitive  fibres,  treated  with 
pyroacetic  acid. 


(fig.  173,  1)  in  the  fresh  intestinal  canal,  with  the  cells  (a)  and 
the  pale  nerve-fibres  (b  c).  Fine  vertical  sections  may  be 
employed,  or  (which  has  proved  to  be  more  suitable)  a  por- 
tion of  the  intestine  may  be  well  stretched,  and  the  muscular 
layer  and  the  mucous  membrane  carefully  dissected  from  both 
sides,  so  that  the  submucous  connective  tissue  remains  isolated. 
Even  without  any  further  addition,  one  may,  with  some  pains, 
discover  a  few  ganglia,  but  as  soon  as  the  connective  tissue  has 
been  rendered  transparent,  by  means  of  very  dilute  acetic  acid, 
the  whole  arrangement  may  be  readily  seen.  Simple  chromic 
acid  preparations  also  frequently  afford  good  specimens,  at  least 
in  vertical  sections. 

The  ganglionic  plexus  mentioned  has  been,  in  an  almost  in- 
comprehensible manner,  asserted  to  be  a  capillary  network. 
All  doubt  may  be  removed  by  injecting  a  portion  of  intestine 
with  Prussian  blue  or  sulphate  of  baryta,  and  immersing  it  in 
pyroacetic  acid  (fig.  172,  c). 

The  plexus  myentericus  (fig.  174)  of  the  larger  mammalia 


MUSCLES  A:NT>  KEKVES.  345 

and  of  man  is  only  to  be  recognized  with  difficulty  and  pains, 
in  consequence  of  the  thickness  of  the  muscular  coat.  Macera- 
tions in  dilute  pyroacetic  acid  or  acetic  acid,  also  appear  to  con- 
stitute the  best  accessories.  The  demonstration  succeeds  very 


Fig.  174.    Plexus  myentericus,  from  the  small  intestine  of  the  Guinea-pig,    a,  nervous  plexus ; 
6,  ganglia ;  c,  lymphatics. 

readily,  on  the  contrary,  with  smaller  animals,  such  as  rabbits, 
but  especially  with  Guinea-pigs,  rats,  and  mice.  A  portion  of 
the  small  intestine,  still  better  of  the  colon  of  a  Guinea-pig, 
immersed  in  purified  pyroacetic  acid  diluted  with  several  times 
its  volume  of  water  (20  to  15  per  cent.),  will  after  24  hours  (or 
even  sooner)  have  acquired  such  a  swollen  and  macerated  con- 
dition as  that  the  mucous  membrane  may  be  readily  removed. 
If  the  thin  muscular  and  serous  layers  be  now  immersed  in 
watery  glycerine,  and  placed  under  the  microscope  with  a  low 
magnifying  power,  a  surface  view  of  the  whole  elegant  nervous 
apparatus  (a  5)  may  be  at  once  obtained.  Here,  as  with  the 
ganglia  of  the  submucous  layer,  care  should  be  taken  to  have 
the  action  of  the  pyroacetic  acid  too  weak  rather  than  too 
strong,  as  otherwise  the  appearance  of  the  cells  and  nerve- 
fibres  is  entirely  altered.  In  all  these  cases  the  acid  contained 


346  SECTION    FIFTEENTH. 

in  the  pyroacetic  acid  solutions  should  be  more  accurately 
determined  by  the  method  of  titrition. 

The  structure  of  the  central  organs  of  the  nervous  system, 
the  spinal  cord  and  brain,  is  so  complicated  and  obscure,  and  at 
the  same  time  the  subject  of  such  frequent  controversy,  that  it 
would  lead  us  far  beyond  the  limits  of  this  book  if  we  were  to 
enter  at  all  into  the  details  of  these  textural  conditions.  "We 
therefore  limit  ourselves  chiefly  to  the  description  of  the  me- 
thods of  investigation  generally  employed  at  present. 

These  may  be  divided  into  two  series :  first,  such  as  are 
intended  for  isolating  the  elementary  structures  ;  and  then  the 
others,  which  are  to  harden  the  central  organs  to  such  a  degree 
as  that  thin  sections  may  be  conveniently  made  from  them,  and 
thus  an  appreciation  of  the  entire  arrangement  obtained.  It  is 
hardly  necessary  to  remark  that  a  thorough  promotion  of  our 
knowledge  requires  the  combination  of  both  these  methods  of 
investigation. 

The  older  investigators  frequently  attempted  to  examine  the 
ganglion-cells  and  nerve-fibres  in  picked  preparations  of  por- 
tions of  brains  and  spinal  cords,  which  were  as  fresh  as  possible, 
as  well  as  of  those  which  were  not  so  fresh.  The  delicate  ner- 
vous structures  are  too  intimately  united  by  the  connective-tissue 
framework,  however,  for  one  to  hope  to  find  more  than  their 
fragments.  And,  in  fact,  we  have  more  recently  discovered 
much  better  and  more  productive  methods.  The  highly  diluted 
solutions  of  chromic  acid,  and  of  the  bichromate  of  potash,  re- 
commended by  Schultze,  constitute  accessories  of  the  first  rank, 
as  they  exert  a  partly  macerating,  partly  hardening  effect  on 
the  various  elements  of  these  organs,  without  producing  any 
deeper  textural  changes. 

The  reader  would  deceive  himself,  however,  if  he  were  to  re- 
gard the  successful  application  of  the  solutions  as  a  relatively  easy 
affair.  Even  after  following  certain  directions,  selecting  only 
fresh,  preferably  still  warm  organs,  and  especially  those  of  the 
larger  mammalia,  such  as  the  ox  and  calf ;  furthermore,  not 
to  place  too  large  pieces  in  a  relatively  small  quantity  of 
fluid ;  there  are,  nevertheless,  many  difficulties  still  remaining. 
Kext  arises  the  problem  of  hitting  upon  the  proper  degree  of 


MUSCLES    AND    NERVES.  347 

concentration  of  these  fluids,  and  this,  lying  within  pretty 
narrow  limits,  requires  careful  experiment,  as  further  differ- 
ences present  themselves  according  to  the  warmth,  nature,  and 
age  of  the  animal.  Solutions  which,  to  the  ounce  of  water, 
contain  more  than  0.1-0.125  gr.  of  the  chromic  acid,  or  more 
than  2  grains  of  its  potash  salt,  are  absolutely  objectionable. 
Even  much  higher  degrees  of  dilution  are  frequently  employed 
with  advantage. 

Let  us  listen  to  Deiters,  the  most  competent  of  the  modern 
investigators  in  this  department  of  technology.  He  recom- 
mends the  immersion  at  first  in  a  solution  of  chromate  of  pot- 
ash, which  contains  0.5  gr.  to  the  ounce,  till  the  second  day, 
whereby  the  desired  result  is  not  unfrequently  obtained.  If. 
the  latter  has  not  yet  taken  place,  or  if  it  be  desired  to  preserve 
the  preparation  for  a  few  days  longer,  this  solution  may  be 
doubled  in  strength  for  an  additional  day,  and  then  increased 
to  2  grains  for  another  twenty-four  hours.  Not  unfrequently 
weaker  than  half-grain  solutions  are  to  be  preferred.  Thus, 
one  may  commence  with  0.125  and  0.25  gr.,  and  then  terminate 
with  0.5  gr. ;  or  solutions  of  chromic  acid  may  be  first  em- 
ployed, and  then  its  salt,  whereby  greater  looseness  of  the  pre- 
paration is  obtained.  The  strength  in  which  the  chromic  acid 
is  employed  is  from  0.033,  0.05  to  0.1  gr.  to  the  ounce.  Two 
days  are  to  be  allowed  to  pass  without  changing  the  fluid ;  on 
the  third  day  it  is  to  be  renewed.  Now,  occasionally  even 
sooner,  a  very  good  degree  of  maceration  for  many  parts  is  ob- 
tained. For  the  combination  of  both  these  methods  it  is  recom- 
mended, after  using  the  chromic  acid  for  two  days,  to  place  the 
piece  in  a  0.5  gr.  solution  of  chromate  of  potash,  then  on  the 
following  day  in  one  of  1  gr.,  afterwards  perhaps  increasing  the 
strength  to  2  grs.  After  this,  to  obtain  a  considerably  mace- 
rated condition  of  the  framework  substance,  such  objects  may 
be  advantageously  exposed  to  the  action  of  extremely  dilute 
solutions  of  the  alkalies.  A  drop  of  a  28  per  cent,  solution  of 
caustic  potash  may  be  added  to  the  ounce  of  water ;  after  hav- 
ing been  exposed  to  this  for  an  hour,  the  preparation  is  to  be 
removed  and  washed  (in  dilate  chromic  acid,  for  instance),  then 
replaced:  in  the  solution  of  chromate  of  potash,  which  should 


348  SECTION    FIFTEENTH. 

contain  at  first  0.5,  the  following  day  1,  afterwards  perhaps  2 
grs.  to  the  ounce. 

The  simpler  of  these  methods,  or  a  combination  of  them  (it 


Fig.  175.  Multipolar  ganglion-cell  from  the  anterior  horn  of  the  spinal  cord  (of  the  ox),  with 
the  axis-cylinder  process  (a),  and  the  branched  protoplasma  processes,  from  which  at  6  the  finest 
filaments  arise  (after  Deiters). 

is  better  to  employ  several  of  them  simultaneously),  will,  to- 
gether with  many  failures,  also  afford  suitable  objects  for  ex- 
amination, although  they  only  continue  to  be  serviceable  for  a 
few  days.  It  is  best  to  remove  a  small  portion  of  the  tissue 


MUSCLES    AND    NEKVES.  349 

with  the  point  of  a  knife,  and  pick  it  apart  as  carefully  as  pos- 
sible. 

With  such  accessories  Deiters  succeeded  in  making  a  re- 
markable discovery  concerning  the  multipolar  ganglion-cells 
of  the  central  organs.  They  (fig.  175)  have  two  kinds  of  pro- 
cesses. The  greater  proportion  of  the  latter  are  only  continua- 
tions of  the  same  protoplasma-like  substance  which  is  presented 
by  the  body  of  the  ganglion-cell.  These  processes,  the  "  pro- 
toplasma  processes'-  of  Deiters,  divide  into  manifold  ramifica- 
tions, until  at  last  they  disappear  as  the  finest  terminal  branches 
in  the  supporting  substance.  At  the  first  glance  an  exceedingly 
long  process  (a)  may  be  distinguished  from  the  protoplasma 
processes,  which  arises  either  from  the  cell-body  itself  or  from 
one  of  the  broadest  of  the  former  processes ;  it  never  presents 
any  ramifications,  and  is  afterwards  covered  by  a  medullary 
sheath.  Deiters  has  called  it  the  "  axis-cylinder  process."  Fi- 
nally, one  may  also  recognize,  passing  off  at  right  angles  from 
the  protoplasma  processes  of  our  multipolar  ganglion-cells,  ex- 
tremely fine  filaments  (5,  £),  which  the  above-mentioned  investi- 
gator believes  to  be  a  second  system  of  extremely  fine  axis- 
cylinders.  „ 

Still  another  method  has  recently  been  recommended  by 
Gerlach,  an  investigator  who  has  accomplished  much  for 
microscopical  technology,  for  isolating  these  ganglia  and  a 
very  fine  nervous  network  (that  is,  their  protoplasma  proces- 
ses) connected  with  them  (of  which,  according  to  his  views,  the 
gray  substance  of  the  spinal  cord  consists).  Thin  longitudinal 
sections  are  to  be  made  with  a  razor,  preferably  through  the 
region  of  the  anterior  horns  of  the  quite  fresh  and  still  warm 
spinal  cord  of  a  mammalial  animal.  These  are  to  be  placed 
for  2-3  days  in  very  weak  solutions  of  the  bichromate  of  am- 
monia (0.01-0.02  per  cent.).  They  are  then  to  be  placed  in  a 
likewise  extremely  dilute  ammoniacal  solution  of  carmine, 
which  produces  the  necessary  tinge  in  about  a  day.  Those 
portions  wrhich  are  thinnest  and  best  tinged  are  then  to  be  care- 
fully picked  apart. 

Still  another  complication  of  the  structure  of  these  ganglion- 
cells  of  the  central  organs  has  been  observed.  According  to 


350 


SECTION    FIFTEENTH. 


Schultze's  investigations,  both  varieties  of  the  processes  of  the 
central  ganglion-cells  (fig.  176)  present  a  fibrillated  structure  ; 
this  is  most  distinct  in  the  axis-cylinder  (a),  however,  while  in 
the  protoplasma  proeesses  (b)  there  is  a  greater  quantity  of 


Fig.  176.     Ganglion-cell  from  the  anterior  horn  of  the  spinal  cord  of  the  ox,  after  Schultze.    a, 
axis-cylinder ;  6,  cell-processes. 

a  granular  intervening  substance.  The  "  primitive  fibrillse " 
(p.  335)  may  be  followed  into  the  body  of  the  ganglion-cell, 
where  .they  are  seen  to  have  a  complicated  course.  This 
arrangement,  first  noticed  by  Remak,  may  be  observed  without 


MUSCLES    AND    NERVES.  351 

difficulty  in  fresh  specimens  simply  moistened  with  serum,  or 
in  osmic  acid  preparations. 

Frommann  asserts  that  he  has  ascertained,  by  treatment  with 
nitrate  of  silver,  that  these  fibrillee  originate  in  the  nucleoli  and 
are  surrounded  like  a  sheath  by  tubes  which  proceed  from  the 
nuclei.  Arnold  also  informs  us  of  similar  results.  He  used 
serum  or  chromic  acid  (0.01  per  cent.)  and  chromate  of  potash 
(0.02-0.05  per  cent.)  as  fluid  media. 

These  points  will  have  to  be  decided  by  future  investigations. 
It  was  supposed,  many  years  ago,  that  the  nerve-fibres  origina- 
ted in  the  nucleolus  and  nucleus  of  the  ganglion-cell  (Harless, 
Axmann,  Lieberkiihn,  Wagener). 

The  art  of  giving  the  substance  of  the  brain  and  spinal  cord 
a  consistence  suitable  for  making  sections  has  been  possessed 
for  many  years. 

Alcohol,  the  solutions  of  chromic  acid  and  of  the  bichromate 
of  potash,  and  ammonia  are  used  for  hardening.  Whether  the 
one  or  the  other  of  these  fluids  is  used,  only  pieces  of  the  brain 
and  spinal  cord  which  are  quite  fresh  and  carefully  removed 
from  the  recently  killed  animal  and  deprived  of  their  envelopes, 
should  ever  be  immersed  in  them.  The  pieces  should  not  be 
too  large.  If  their  volume  be  too  large,  the  exterior  may 
acquire  a  good  consistence,  but  the  central  portions  will,  on  the 
contrary,  remain  soft  or  even  become  decomposed.  I  would 
recommend,  as  a  useful  method,  to  allow  such  pieces  to  float  in 
a  tall  glass  cylinder,  suspended  by  means  of  a  silk  thread  to  a 
hook  in  the  glass  stopper. 

Among  the  reagents  mentioned,  alcohol  takes  the  lowest 
place.  Preference  has  therefore,  for  many  years,  been  given 
to  solutions  of  chromic  acid  and  the  chromate  of  potash.  Here 
we  must  also  censure  the  custom  of  estimating  the  strength  of 
these  solutions  only  by  their  color.  Now  and  then  the  proper 
degree  of  concentration  may  be  obtained  in  this  way ;  but  in 
many  cases  one  will  be  deceived  and  fail  in  obtaining  the 
desired  result,  which  might  have  been  accomplished  with  less 
trouble  by  making  an  accurate  solution. 

ISTow,  what  degree  of  concentration  should  be  given  to  such 
solutions  ?  Here  it  must  be  remembered  that  the  fluids  used 


352  SECTION   FIFTEENTH. 

by  former  observers  were  generally  much  too  strong,  so  that  a 
considerable  shrinking  of  the  tissues  took  place,  and  not  unfre- 
quently  the  whole  became  entirely  too  brittle  to  permit  of  a 
section  being  made.  A  chromic  acid  solution  of  1  per  cent,  is 
certainly  too  strong  for  commencing  the  hardening.  I  have 
obtained  good  results  with  mammalial  animals  as  well  as  with 
cold-blooded  vertebrates,  such  as  fishes  and  frogs,  when  I  com- 
menced the  hardening  with  solutions  of  0.2  per  cent. ;  then  changed 
the  chromic  acid  after  a  few  days,  replaced  it  by  a  stronger  so- 
lution, and  thus  finally  arriving  at  those  of  1  per  cent.  Chro- 
mate  of  potash  is  to  be  used  in  the  corresponding  strength  of 
2-6  per  cent.  (comp.  p.  139).  Deiters  employed  the  following 
method  for  hardening  the  brain  and  spinal  cord  :  He  first  im- 
merses the  preparation  for  one  or  two  weeks  in  a  solution  of 
the  chromate  of  potash  (15  grains  to  the  ounce  of  water).  Then 
(when  a  uniform  saturation  has  taken  place  and  the  hardening 
has  commenced)  the  preparation  is  placed  either  immediately 
or  after  washing  out  the  potash  salt,  in  a  solution  of  chromic 
acid  which  contains  2  grains  to  the  ounce  and  may  be  increased 
to  3  grains. 

Gerlach  recommends  the  use  of  a  1-2  per  cent,  solution  of  the 
bichromate  of  ammonia  for  at  least  fifteen  or  twenty  days,  occa- 
sionally for  five  weeks. 

It  is  impossible  to  state  anything  definite  with  regard  to  the 
time  which  is  generally  required  for  the  hardening.  Chromic 
acid  salts  act  more  slowly,  the  free  acids  more  rapidly.  I  have 
often  found  that  the  spinal  cord  of  small  animals  has  become 
sufficiently  firm  in  a  week  in  these  solutions  of  the  free  acid. 
As  a  rule,  a  space  of  three  to  four  weeks,  not  unfrequently  still 
longer — six  weeks  or  more,  is  necessary.  There  is  great  varia- 
tion, however,  in  this  regard.  Reissner  is  therefore  correct  in 
asserting  that  the  central  parts,  especially  the  spinal  cord  of  the 
various  kinds  of  animals,  also  show  differences  in  regard  to  the 
time  which  is  requisite  to  harden  them.  It  is  generally  stated, 
it  is  true,  that  the  hardening  takes  place  more  rapidly  with 
small  animals  than  with  those  which  are  larger.  This  is,  how- 
ever, by  no  means  universally  the  case,  as,  according  to  his 
experience,  the  spinal  cord  of  the  calf  becomes  hard  in 


MUSCLES    AND    NERVES.  353 

weaker  solutions  than  does  that  of  the  rabbit,  the  mouse,  or  the 
rat. 

To  ascertain  the  proper  degree  of  consistence,  nothing  further 
is  necessary  than  to  make  a  trial  section  with  the  razor  from 
time  to  time.  The  hardening  should  have  progressed  in  exactly 
such  a  manner  as  that  with  the  moistened  blade,  a  very  thin 
layer  may  be  removed  conveniently  and  without  crumbling. 
If  the  tissue  crumbles  it  is  already  overhardened ;  if  the  consis- 
tence is  insufficient,  only  thick  sections  are  possible.  In  the 
latter  case  a  further  immersion  is  necessary;  in  the  former,  the 
procedure  is  a  failure. 

If  one  has  been  so  successful  as  to  have  obtained  the  proper 
consistence,  the  hardened  object  is  to  be  placed,  after  having 
been  washed,  in  weak  watery  alcohol.  It  may  be  preserved  in 
this  for  a  long  time  without  undergoing  any  changes,  to  serve 
for  future  investigations. 

With  some  practice  and  a  good  razor  one  soon  learns  to  make 
marvellously  thin  sections.  In  doing  this,  the  object  is  to  be 
held  with  the  points  of  the  first  three  fingers  of  the  left  hand, 
and  care  is  to  be  taken  to  keep  the  preparation  and  the  blade 
sufficiently  moistened  with  alcohol.  It  is  impossible  to  hold 
very  small  objects,  such  as  the  spinal  cord  of  a  mouse,  for  in- 
stance, with  the  points  of  the  fingers.  They  may  be  placed  in 
a  larger  animal  body,  the  spinal  cord  of  a  larger  animal  for  in- 
stance, or  in  a  piece  of  elder  pith ;  or  an  embedding  method 
(p.  117)  may  be  employed. 

Sections  made  in  all  directions  are  naturally  necessary,  in 
order  to  construe  from  the  various  preparations  the  structure  of 
such  central  parts  as  the  spinal  cord,  for  example.  Transverse 
sections  are  first  made,  then  longitudinal  ones,  of  which  vertical 
and  horizontal  longitudinal  as  well  as  oblique  (that  is,  such  as 
are  made,  for  instance,  from  the  right  posterior  cornua  towards 
the  left  anterior  cornua)  sections  are  of  importance.  Those 
which  are  made  oblique  to  the  long  axis  of  the  cord  appear  to 
be  of  less  importance. 

For  most  examinations  it  is  advantageous  to  tinge  the  sections 
thus  obtained.  Staining  with  carmine  is  nowadays  generally 

employed  in  these  cases. 
23 


354  SECTION    FIFTEENTH. 

Here,  as  with  all  delicate  tissues,  I  employ  a  solution  of  car- 
mine obtained  with  a  minimum  of  ammonia,  which  is  to  be  con- 
siderably diluted  with  water,  and  then  an  equal  volume  of  gly- 
cerine added.  The  sections  are  to  be  washed  out  in  very  dilute 
alcohol,  to  free  them  from  any  chromic  acid  which  may  be  pre- 
sent, and  then  placed  in  the  solution  to  acquire  the  desired  red- 
ness, for  which  two,  four,  eight  to  twelve  hours  is  necessary, 
according  to  the  concentration  of  the  coloring  medium. 

The  object  is  next  to  be  placed  for  a  short  time  in  clean 
water  to  wash  out  the  superfluous  carmine,  then  in  water  very 
slightly  acidulated  with  a  few  drops  of  acetic  acid,  or  in  dilute 
alcohol  thus  acidulated.  The  diffuse  redness  disappears,  and 
the  remaining  carmine  is  then  fixed  to  the  cells,  nuclei,  and 
axis-cylinders.  If  individual  differences  occur  with  regard  to 
the  capability  of  imbibition  of  the  tissue  elements  of  the  brain 
and  spinal  cord,  the  epithelium,  ganglion  bodies,  axis-cylinders, 
and  the  nuclei  of  the  connective-tissue  framework  are  to 
be  designated  as  those  parts  which  become  especially  impreg- 
nated with  the  coloring  matter. 

Preparations  thus  treated  may  be  examined  in  a  moist  condi- 
tion. A  solution  of  the  chloride  of  calcium  has  been  recom- 
mended for  rendering  them  more  transparent  (Schroder  van 
der  Kolk).  I  must  acknowledge,  with  Reissner,  that  I  have 
accomplished  nothing  with  this.  Glycerine  renders  better  and 
satisfactory  service  in  this  case. 

The  preparation  may  be  rendered  more  permanently  trans- 
parent, however,  by  immersing  it,  after  it  has  been  carefully  and 
cautiously  deprived  of  its  water,  in  oil  of  turpentine  or  Canada 
balsam.  This  method  is  the  most  popular  at  present,  and  also 
affords  the  most  beautiful  and  most  durable  preparations  for  a 
collection.  We  refer  for  it  to  page  207  of  our  book.* 


*  We  here  add  several  other  methods  : — 

1.  Years  ago  Lockhart  Clarke,  who  was  afterwards  imitated  by  Lenhossek, 
made  use  of  the  following  process  :  The  fresh  spinal  cord  is  to  be  hardened  in 
alcohol ;  the  first  day  it  is  to  be  placed  in  such  as  is  diluted  with  an  equal  vol- 
ume of  water,  then  left  in  pure  alcohol  until  thin  sections  are  possible,  a  con- 
dition which  is  generally  obtained,  in  the  cooler  portion  of  the  year,  in  from 
5-6  days.  The  sections  are  then  to  be  immersed  for  1-2  hours  in  the  mixture 


MUSCLES    AND    NERVES.  355 

If  it  be  desired  to  tinge  blue,  the  soluble  aniline  blue  of  the 
strength  previously  mentioned  (see  p.  157)  affords,  after  some- 
what energetic  action,  handsome  and  permanent  preparations ; 
the  hsematoxylin.  (p.  158)  is  still  finer.  Osmic  acid,  which  acts 
in  the  manner  indicated  at  page  163,  not  only  on  such  sections, 
but  likewise  on  such  as  have  been  tinged  with  carmine  also, 
promises  to  be  of  importance  (M.  Schultze). 

Several  years  ago  Gerlach  praised  the  treatment  with  chloride 
of  gold  and  potash  (p.  165)  as  an  excellent  means  of  rendering 
the  course  of  the  nerve-fibres  in  the  spinal  cord  visible. 

Fine  transverse  sections  are  made  from  the  spinal  cord  after 
it  has  been  hardened  by  immersion  for  3-6  weeks  in  a  solution 
of  the  bichromate  of  ammonia.  The  sections  are  to  be  placed 
for  10  or  12  hours  in  a  0.01  per  cent,  solution  of  the  gold  salt 
to  which  a  little  acetic  or  muriatic  acid  has  been  added.  Then 
(when  the  white  substance  has  gained  a  pale  lilac  color,  and  the 
gray  presents  but  a  slight  tinge),  the  section  is  to  be  washed  with 
a  to-and-fro  movement,  continued  for  several  minutes  in  very 
dilute  hydrochloric  acid  (1  :  2-3000).  Gerlach  now  places  it 
for  about  10  minutes  in  a  mixture  of  1  part  muriatic  acid  and 
1000  parts  alcohol  of  60  per  cent.,  and  afterwards,  finally,  for  a 
few  minutes  in  absolute  alcohol.  Oil  of  cloves  serves  to  render 
the  section  transparent,  and  it  is  then  mounted  in  Canada  bal- 
sam, which  terminates  this  somewhat  complicated  process.  To 
render  the  ganglion-cells  visible,  it  is  necessary,  before  immers- 
ing the  preparation  in  the  gold  salt,  to  employ  one  of  the  other 
methods  of  metallic  impregnation  for  several  hours,  such  as 
that  with  chloride  of  palladium  (p.  165),  or,  which  the  author 

mentioned  at  page  142,  consisting  of  1  part  acetic  acid  and  3  parts  alcohol. 
In  this,  not  only  the  nerves  and  fibrous  elements  are  rendered  more  sharply 
prominent,  but  the  gray  substance  is  also  rendered  quite  transparent. 

2.  J.  Dean,  to  whom  we  are  indebted  for  a  very  superior  work  on  the  cen- 
tral organ,  hardens  in  alcohol  or  chromic  acid,  and  colors  the  washed  sections 
moderately  in  glycerine -carmine,  in  which  they  remain  from  4-8  hours, 
according  to  the  intensity  of  color  desired.  Alcohol,  oil  of  turpentine,  and 
Canada  balsam  are  then  employed.  According  to  Dean,  thick  copal  varnish  is 
often  preferable  to  the  balsam  for  the  recognition  of  fine  details.  Dean  also 
praises  Clarke's  method  highly,  and,  we  will  add,  very  appropriately,  if  the 
mixture  is  allowed  to  act  on  tinged  preparations. 


356  SECTION   FIFTEENTH. 

prefers,  to  make  use  of  a  very  dilute  solution  of  a  metallic  salt 
which  has  not  been  previously  employed  in  histology,  the  nitrate 
of  uranium. 

With  industry  and  perseverance,  and  by  the  aid  of  the 
methods  of  preparation  which  have  been  given,  one  may  suc- 
ceed in  recognizing  the  more  important  textural  relations  of 
the  spinal  cord  (those  of  the  brain  with  greater  difficulty), 
whereby,  as  was  remarked,  the  examinations  should  commence 
with  transverse  sections.  At  the  same  time  one  will  also  recog- 
nize the  great  difficulty  of  accurately  describing  the  textures  of 
the  central  organs — a  difficulty  which  is  founded  in  part  on  the 
nature  of  the  object ;  in  part,  also,  on  the  methods  of  investiga- 
tion, which  still  remain  insufficient.  Many  observers  have  cer- 
tainly exaggerated  the  results  of  their  investigations  very  much, 
frequently  drawing  very  false  conclusions  from  fragmentary, 
isolated  appearances.  Other  investigators  have,  however,  be- 
come infected !  with  an  excessive  skepticism.  Attempts  have 
even  been  made  to  disprove  the  reticulated  commissural  com- 
munication of  the  large  multipolar  gangliohic  bodies  in  the 
anterior  cornua  of  the  spinal  cord,  as  also  the  continuation  of 
some  of  their  processes  into  nerve- fibres  of  the  anterior  motor 
root.  In  our  opinion  these  textural  conditions  may  be  observed 
with  entire  certainty,  although  only  with  difficulty  and  on  very 
rare  occasions. 

To  obtain  injected  preparations  of  the  brain  and  spinal  cord, 
one  should  proceed  in  the  following  manner.  One  of  the 
smaller  mammalia,  a  rat,  a  Guinea-pig,  a  rabbit,  or  a  cat  may 
be  selected,  and  the  canula  inserted  into  the  commencement  of 
the  aorta,  after  this  vessel  has  been  ligated  below  the  carotids 
and  the  subclavians.  The  injection  readily  succeeds  on  the 
fresh  body  (with  some  loss  of  injecting  fluid,  it  is  true)  with 
cautious  management  of  the  syringe.  But  to  judge  of  the  correct 
moment  for  terminating  the  procedure  is  somewhat  difficult. 
If  a  white  rat  or  an  Albino  rabbit  has  been  used,  the  complete 
injection  of  the  eyeball  affords  a  criterion.  To  inject  the 
upper  half  of  the  spinal  cord,  the  aorta  is  to  be  ligated  as  it 
passes  through  the  diaphragm,  and  the  procedure  completed  as 
above  mentioned.  Deep-red  carmine-gelatine  constitutes  the 


MUSCLES    AND    NERVES.  357 

best  injection  fluid.  Alcohol  is  used  for  hardening,  and  a  blue 
tincture  for  staining  the  sections.  Prussian  blue  is  to  be  pre- 
ferred, if  it  be  desired  to  accomplish  the  former  with  chromic 
acid. 

The  blood-vessels  in  the  central  organs  are  loosely  enveloped 
by  a  connective-tissue  adventitia,  and,  according  to  the  interest- 
ing testimony  of  His,  the  lymph  flows  in  the  intervening  space 
which  is  thus  formed.  This  vaginal  space  may  be  readily  in- 
jected by  means  of  the  puncturing  method.  A  similar  vaginal 
formation  may  also  be  seen  around  the  blood-vessels  of  the  pia 
mater  (peri vascular  space  of  His). 

A  further  difficulty  in  the  investigation  of  the  central  organ 
of  the  nervous  system  is  found  in  distinguishing  the  connective- 
tissue  framework  (neuroglia)  from  the  nervous  elements. 
Although  the  tacit  presumption,  that  everything  which  is 
present  in  the  brain  and  spinal  cord  must  also  be  of  a  nervous 
nature,  was  accepted  for  many  years,  the  extensive  occurrence 
of  a  connective-tissue  substance,  in  which  the  nervous- tissue 
elements  are  imbedded,  was  afterwards  rightly  maintained  by 
Bidder  and  his  followers,  although  with  some  exaggeration. 

There  is  repeated  in  the  brain  and  spinal  cord,  therefore,  one 
of  those  undeveloped,  reticular  connective  substances,  such  as 
have  been  frequently  observed  of  late  in  the  human  body — one 
of  those  reticulations  and  frameworks  with  cell-bodies  in  some 
of  the  nodal  points. 

In  the  white  substance,  this  is  of  a  more 
compact  structure,  and  appears  in  transverse 
sections  as  a  network  with  isolated  nuclei  and 
round  apertures  for  the  reception  of  the 
nerves  (fig.  177). 

The  reticular  connective  tissue  in  the  c«r- 
tical  layer  of  the  white  substance  passes  un- 
interruptedly  into  the  pia  mater,  where  it  is 
more  richly  developed  and  the  reticulations    Bpmalcord- 
become  very  much  finer. 

The  reticular  framework  of  the  gray  substance  of  the  spinal 
cord  likewise  appears  to  be  extraordinarily  delicate,  and  fre- 
quently the  meshes  are  extremely  fine.  This  also  appears  ex- 


358  SECTION   FIFTEENTH. 

tremely   developed  and  with   distinctly  radiated   connective- 

tissue  cells  in  the  interior  of  the  so-called  central  thread  of 

ependyma. 

Such  a  supporting  substance  certainly  occurs 
in  the  brain  also,  although  not  so  well  known 
(fig.  178).  In  the  gray  substance  of  the  cortex, 
the  network,  which  has  nuclei  in  its  nodal 
points,  assumes  an  infinite  fineness  and  delicacy 
of  its  fibres  and  meshes,  so  that  its  existence  has 
frequently  been  totally  denied. 

Methods  of  maceration  such  as  were  recom- 
mended by  Deiters  (p.  347)  serve  for  the  recog- 

flsue  o?'th«F°S£y    nition  of    these  framework   substances,  which 
are  a^so  extremely  important  for  the  pathologists. 


iy™diLuteh  *d!romio     ^ne  action  of  nitrate  of  silver  on  segments  of 
the  fresh  tissue,  with  a  subsequent  addition  of 
glycerine,  has  also  been  used  with  success  (Frommann)  ;  like- 
wise osmic  acid. 

Gerlach  recommends  the  two  methods  of  treatment  with 
chloride  of  gold  and  potash  and  carmine,  mentioned  above  (p. 
355),  for  distinguishing  the  neuroglia  of  the  gray  substance 
from  the  very  fine  network  of  nerve-fibres  which  also  occurs 
there.  Only  the  nervous  elements,  but  not  those  of  the  connec- 
tive tissue,  become  colored.  For  the  diagnosis  of  nervous  and 
connective-tissue  cells  in  them,  a  suitable 
reagent  is  still  wanting. 

Tumor-like  new  formations  of  the  f  rame- 
work  substance  mentioned  occur  in  the 
central  organs  and  in  the  retina.  They 
have  been  called  glioma  (Yirchow). 

•     /^v  A  deposit  of  peculiar   structures,  fre- 

^GBp  quently  discussed  of  late,  the  so-called  amy- 

ig.  179.  Amyloid  cor-      loid  bodies,  corpuscula  amylacea  (Fig.  179), 
kumau      takes  place  in  this  framework  substance 
after  death,  as  a  result  of  decomposition, 
and  even  during  life  in  abnormal  conditions. 

These,  varying  in  size,  occur  as  globular,  ovoid,  or  double- 
loaf-shaped  structures,  in  which  a  distinctly  stratified  appearance 


8 


MUSCLES    AND    NERVES. 


359 


may  frequently  be  recognized  under  the  microscope.  In  these 
cases  they  remind  one  very  much  of  amylon  granules,  for 
which  they  have  also  been  mistaken.  Their  reaction  may  be 
that  of  amylon,  taking  a  blue  color  with  a  solution  of  iodine. 
Others,  on  the  contrary,  assume  a  violet  hue  from  the  action 
of  iodine  and  sulphuric  acid  (see  p.  136),  and  put  one  in  mind 
of  cellulose. 

In  addition,  let  it  be  remarked  that  similarly  reacting  masses 
may  also  make  their  appearance  in  many  other  parts  of  the 
body,  and  an  amyloid  degeneration  has  consequently  been  re- 
cently assumed. 

As  we  are  at  present  referring  to  chemical  matters,  let  us 
also  at  the  same  time  mention  the  so-called  myeline.  It  appears 
under  the  microscope  in  the  form  of  double  contoured  drops 
and  lump-like  masses,  and  is  also  not  limited  to  the  nervous 
system. 

Our  fig.  180,  in  its  lower  half,  may  afford  us  a  representation 
of  this  optical  peculiarity  of  that  substance.  The  upper  portion 


Fig.  180.  Crystals  of  cholesterine  and  deposits  of  myelino. 

of  the  drawing  is  occupied  by  crystals  of  cholesterine,  a  pecu- 
liar substance,   widely  spread  throughout  the  animal    body 


360  SECTION    FIFTEENTH. 

(which  has  also  been  more  recently  discovered  by  Beneke  and 
Kolbe  in  plants).  This  cholesterine  forms  an  element  of  the 
nerve-substance ;  it  also  occurs  in  the  blood,  though  in  small 
quantity,  more  abundantly  in  the  bile  (and  especially  in  the 
biliary  calculi) ;  likewise  in  most  of  the  other  animal  fluids,  with 
the  exception  of  the  urine.  Finally,  it  occurs  in  pathological 
fluids  and  tumors,  and  has  the  signification  of  a  product  of  de- 
composition. 

It  occurs  in  very  delicate,  thin,  rhomboidal  tables  (with  acute 
angles  of  79°  30',  also  of  87°  30',  and  of  only  57°  20'),  and  is 
thus  for  the  most  part  readily  recognizable.  It  likewise  shows 
certain  characteristic  reactions.  If  a  mixture  of  5  parts  of  sul- 
phuric acid  (of  1.85  sp.  wt.)  and  1  part  of  water  be  added  to 
the  crystals  of  our  substance  under  the  microscope,  a  peculiar 
change  of  colors  takes  place.  The  borders  of  the  tablets  be- 
come carmine  red,  then,  with  a  commencing  dissolution  into 
drops,  violet.  If  iodine  and  sulphuric  acid  be  applied,  pure 
cholesterine  assumes  a  blue ;  impure,  a  violet,  reddish,  or  vari- 
egated color.  The  whole  affords  a  beautiful  microscopical 
image,  but  is,  as  a  rule,  without  any  practical  value,  as  the 
shape  of  the  crystals  is  for  the  most  part  entirely  sufficient 
for  the  recognition  of  cholesterine. 

We  have,  finally,  to  mention  the  methods  of  investigation 
which  are  used  at  present  for  the  recognition  of  the  termina- 
tions of  the  nerves. 

These  vary  exceedingly,  according  to  the  constitution  of  the 
part  to  be  investigated,  as,  together  with  the  examination  of  the 
freshest  possible  and  the  altered  elements,  there  is  also  an  in- 
numerable quantity  of  methods  employed  which  vary  with  the 
parts  of  the  body. 

Let  us  commence  with  the  manner  of  termination  of  the  motor 
nerves,  especially  those  in  the  transversely  striated  muscles. 

The  tissue  taken  from  an  animal  which  has  just  been  killed 
is  to  be  first  employed,  as,  immediately  before  the  rigor  mortis 
takes  place,  the  muscular  filaments  present  a  considerable  degree 
of  transparency,  which  soon  gives  place  to  a  more  cloudy  condi- 
tion. In  such  investigations  the  object  is  to  be  examined  either 
without  any  fluid  medium,  and  covered  with  a  thin  glass  scale 


MUSCLES   AND    NERVES. 


361 


only  (which  may,  at  the  most,  be  very  carefully  pressed  upon, 
to  give  a  smooth  surface),  or  with  the  addition  of  indifferent 
fluids.  Only  certain,  especially  thin  membranous  muscles,  are 
adapted  for  such  investigations. 

The  orbital  muscles  of  small  mammalial  animals,  and  among 


Fig.  181.  Radiation  of  the  nerves  in  the  voluntary  mtiscles  of  the  frog.  A  nerve-fibre,  a,  with- 
out a  neurilemma,  with  repeated  subdivisions  into  several  smaller  branches,  6,  6  ;  c,  a  nerve- 
fibre  with  a  neurilemma  of  the  simplest  kind,  without  division. 

these  the  retractor  bulbi  (of  the  cat),  also  the  psoas  muscle  of 
these  animals,  furthermore  the  flat  muscles  which  pass  from 


362  SECTION    FIFTEENTH. 

the  hyoid  bone  to  the  lower  jaw  of  the  frog,  and  the  cutaneous 
thoracic  muscle  of  this  animal,  the  very  short  muscles  in  the  tail 
of  the  lizard,  etc.,  may  be  advantageously  employed. 

One  may  also,  without  trouble,  succeed  in  obtaining  appear- 
ances like  our  fig.  181,  with  suitable  preparations,  from  the 
frog.  The  division  of  the  dark-bordered  primitive  fibres  into 
medullated  branches,  and  their  continued  splitting  up  into  finer 
dark  ones,  may  be  followed,  until  at  last  fine  terminal  branches 
appear  to  end  in  the  muscular  filaments.  It  was  believed  for 
many  years,  in  fact,  that  we  had  thus  penetrated  to  the  ultimate 
terminal  branches. 

A  series  of  investigations  lately  undertaken  shows  that  these 
earlier  views  are  at  all  events  untenable,  and  that  the  nerve-dis- 
tribution takes  place  beyond  these  alleged  terminal  branches. 
The  results  of  the  observations  instituted  by  Kuhne,  Margo, 
Kolliker,  Houget,  Krause,  Engelmann,  and  others  do  not,  how- 
ever, agree.  Still,  after  unprejudiced  examination,  it  can  no 
longer  be  doubted  that  the  nerve  perforates  the  sarcolemma 
(whereby  its  neurilemma  becomes  continuous  with  the  latter), 
and  terminates  beneath  it  in  a  nucleated,  fine,  granular,  lamel- 
lated  substance.  The  latter,  however,  pass  at  their  borders  and 
inner  surfaces  uninterruptedly  into  the  sarcous  substance  of  the 
muscular  filaments  (Kouget,  Engelmann). 

Our  fig.  182  shows  the  terminal  structures  in  question,  which 
have  been  suitably  designated  by  the  name  of  "  terminal 
plates,"  from  the  psoas  of  the  Guinea-pig,  at  the  left  in  profile, 
at  the  right  as  seen  from  above.  In  mammalia,  in  which  they 
are  well  developed,  the  terminal  plates  have  a  magnitude  vary- 
ing in  the  mean  between  0.01T7  and  0.02677".  The  number 
of  their  nuclei  fluctuates  between  4,  6,  10,  and  20. 

The  terminal  plates  become  more  and  more  simplified  in  the 
lower  vertebrates. 

As  has  been  shown  by  more  recent  investigations  (Kiihne, 
Engelmann),  however,  these  terminal  plates  do  not  represent 
the  entire  arrangement.  Suitable  profile  views  show  that  the 
axis-cylinder  becomes  divided  and  spread  out  into  a  tree-shaped 
figure  in  the  external  portion  of  the  terminal  plate.  Beneath 
it,  "  like  a  sole,"  lies  the  granular  nucleated  mass. 


MUSCLES    AKD    NERVES. 


363 


Most  of  the  accessories  which  have  thus  far  been  employed 
are  intended  to  render  the  whole  muscle,  or  at  least  a  part  of 
it,  as  transparent  as  possible,  so  that  the  distribution  of  the 
nerve-fibres  may  be  better  followed  than  in  xthe  unaltered 


Fig.  182.  Two  muscular  filaments  from  the  psoas  of  the  Guinea-pig,  a  6,  the  primitive  fibres 
and  their  continuation  into  the  two  terminal  plates  e  f;  c,  neurilemma  continuous  with  the 
sarcolemma  g  a  >'  At  muscular  nuclei. 

tissue  ;  and  secondly,  to  isolate  the  transversely  striated  muscu- 
lar filaments  with  as  little  injury  as  possible,  and  subject  them 
to  examination  freed  from  their  interstitial'  connective  tissue. 

The  alkalies  are  unserviceable  for  the  former  purpose,  but 
various  acids,  highly  diluted,  are,  on  the  contrary,  very  good. 

Kolliker  recommends  the  dilution  of  8, 12-16  drops  of  acidum 
acet.  concent,  of  the  Bavarian  Pharmacopeia,  of  1.045  sp.  wt, 
with  water  to  100  ccm.,  and  to  immerse  in  it  the  cutaneous  tho- 
racic muscle  of  the  frog  for  1 J-2  hours,  after  which  time  it  is 
said  to  become  transparent  like  glass.  I  have  accomplished  the 
same  result  with  1-2  drops  of  hydrated  acetic  acid  to  50  ccm. 


364  SECTION   FIFTEENTH. 

of  water.  Highly  diluted  acetic  acid  also  proves  very  service- 
able for  the  muscles  of  other  animals  (Engelmann).  I  would 
also  give  this  acid  the  first  rank  for  such  purposes.  Muscles 
which  have  thus  been  rendered  transparent  may  be  preserved 
for  some  time  in  1—2  per  cent,  acetic  acid. 

Muriatic  acid  of  0.1  per  cent,  is  like  wis^j  suitable  reagent. 
It  produces  a  similar  condition  of  the  muscle  in  from  eight  to 
twelve  hours  at  the  ordinary  temperature  of  the  room. 

The  action  for  twenty-four  hours  of  nitric  acid,  of  the  same 
concentration  as  the  hydrochloric  acid,  is  also  serviceable. 

Cohnheim  recommends  the  treatment  with  nitrate  of  silver, 
likewise  with  chloride  of  gold,  in.  which  Krause  agrees. 

The  still  living  muscular  fibres,  fortunately  isolated  by  me- 
chanical means,  often  give  the  most  characteristic  appearances. 

We  have  received  from  Klihne  a  good  method  for  the  further 
isolation  of  the  muscular  filaments  (naturally,  with  as  little  in- 
jury as  possible). 

He  was  able,  by  means  of  the  mixture  of  nitric  acid  and 
chlorate  of  potash,  mentioned  above  at  the  muscular  tissue, 
p.  319,  to  isolate  the  muscular  filaments  with  the  adherent 
nerve-fibres  very  handsomely ;  but  it  was  impossible  to  ascer- 
tain the  further  distribution  of  the  latter.  On  the  contrary, 
the  treatment  which  we  have  also  mentioned,  with  extremely 
dilute  sulphuric  acid,  and  the  subsequent  digestion  in  water, 
constitutes  a  very  suitable  process. 

Krause  recommends,  furthermore,  the  immersion  of  the 
muscles  for  several  days  in  a  33  per  cent,  solution  of  acetic  acid, 
and  then  the  isolation  of  the  filaments  by  careful  picking  from 
the  swollen  connective  tissue.  He  also  obtained  good  prepara- 
tions by  placing  them  in  a  2  per  cent,  solution  of  the  chromate 
of  potash,  with  the  subsequent  action  of  25  per  cent,  acetic  acid. 
He  furthermore  praises  solutions  of  sublimate  of  0.3-0.5  per 
cent.,  and  the  subsequent  treatment  with  the  same  acid ;  and 
finally,  sulphuric  acid  of  0.1  per  cent. 

The  so  readily  decomposable  structures  of  warm-blooded 
animals  are  less  to  be  recommended  than  those  of  the  scaly  am- 
phibiae  for  seeing  the  arborescent  distribution  of  the  nerve- 
fibres  in  the  terminal  plates.  A  lizard  or  a  ring-snake,  killed 


MUSCLES    AND    NEKVES. 


365 


twenty-four  hours  previously  by  destroying  the  central  nervous 
system,  presents,  with  the  addition  of  a  0.5  per  cent,  solution  of 
chloride  of  sodium,  very  characteristic  appearances  (Engel- 
mann). 

It  is  much  more  difficult  to  follow  the  terminal  forms  of  the 
nerve-fibres  in  the  smooth  muscles  than  in  the  transversely 
striated  tissue,  and  our  knowledge  is  therefore  very  uncertain  on 
this  point.  The  broad  ligaments  of  the  uterus  of  the  rabbit 
(Frankenhauser),  likewise  the  urinary  bladder  and  the  small 
arteries  of  the  frog  (Klebs,  Arnold),  are  at  present  considered 
the  most  suitable  objects  for  examination.  Highly  diluted  ace- 
tic and  chromic  acids  are  to  be  tried  here.  Klebs  recommends 
a  5  per  cent,  solution  of  cane-sugar  to  which  sulphurous  acid  is 
added,  and  the  subsequent  immersion  in  phosphate  of  soda. 
Frankenhauser  advises  highly  diluted  chromic  acid,  -fa— fa  per 
cent,  and  also  acetic  acid  of  20  per  cent.  Finally,  we  are  in- 


Fig.  183.  Alleged  nerve-termination  in  the  muscular  coat  of  a  small  artery  of  the  frog,  after 
Arnold. 

debted  to  Arnold  for  very  accurate  directions.  The  object  is 
to  be  placed  for  two  to  four  minutes  in  4  ccm.  of  acetic  acid 
of  0.5-1  per  cent.,  and  then  for  half  an  hour  in  the  same  quan- 


366  SECTION   FIFTEENTH. 

tity  of  chromic  acid  of  0.01  per  cent.  .This  investigator  found 
the  gold  method,  and  likewise  the  treatment  of  transverse  sec- 
tions of  frozen  muscles  with  chloride  of  gold  and  chromic  acid 
solutions,  advantageous. 

According  to  the  investigations  of  Frankenhauser  and  Arnold, 
however,  the  termination  is  very  peculiar.  These  nerves  form 
manifold  networks.  A  secondary  plexus  of  this  kind  lies  close 
to  the  muscular  layer  (fig.  183).  It  consists  of  fine,  pale,  nu- 
cleated filaments.  Still  finer  fibres  spring  from  it  to  form  a 
new  network  with  small  meshes,  the  extremely  fine  terminal 
fibrillse  of  which  are  said  to  end  in  the  nncleoli  of  the  contrac- 
tile fibre-cells.  This  condition  may  be  represented  to  the  reader 
by  the  above  figure.  The  correctness  of  this  statement  has 
of  late,  however,  again  become  very  questionable.  Engelmann, 
in  a  re-examination,  was  unable  to  see  any  trace  of  this  manner 
of  termination — and  we  have  been  equally  unfortunate. 

The  nerves  of  the  cornea  of  the  eye,  which  have  been  for-' 
merly  and  recently  frequently  examined,  present  interesting 
objects  to  the  microscopist. 

Soon  after  entering  the  cornea  at  its  periphery  they  lose 
their  medullary  sheath,  become  pale,  and  form  a  plexus  which 
permeates  the  cornea!  tissue,  of  very  fine  fibrillse  with  nuclea- 
ted enlargements  at  their  nodal  points.  Nerve-fibres  pass  from 
this  network  in  two  directions  :  those  which  proceed  in  the  one 
direction  terminate  in  the  corneal  tissue  itself ;  while  the  others, 
after  perforating  the  anterior  homogeneous  limiting  layer 
(Hoyer),  find  their  terminus  in  the  epithelium  (Cohnheim). 

The  cornea  removed  from  an  animal  immediately  after 
death,  is  naturally  to  be  employed  for  examination.  One  may 
here,  for  example,  with  the  cornea  of  a  frog,  proceed  in 
the  following  manner  (Kuhne) :  The  point  of  a  knife-blade  is 
to  be  inserted  near  the  sclerotic  border,  and  the  aqueous  humor 
drawn  out  with  a  pipette  ;  the  cornea  is  to  be  rapidly  separa- 
ted with  a  pair  of  fine  sharp  scissors  and  placed  on  a  slide,  with 
the  small  quantity  of  aqueous  humor  from  the  pipette.  The 
whole  is  then  placed  in  the  previously  (p.  103)  described  moist 
chamber,  to  remain  for  hours  under  the  microscope,  and  at  the 
same  time  to  gradually  reveal  not  only  the  course  of  the  nerves, 


MUSCLES    AKD    NEEVES. 


367 


but  also  many  other  remarkable  things  in  the  most  conservative 
manner. 

The  procedure  mentioned  may  also  be  used,  with  slight  mod- 
ifications, for  other  animals.  The  cornese  of  the  smaller 
animals,  the  mouse,  the  rat,  and  the  squirrel,  are  generally  to  be 
recommended.  They  are  to  be  removed  in  connection  with  a 
narrow  zone  of  the  sclerotic,  and  it  will  generally  be  necessary 
to  make  several  incisions  in  the  direction  of  the  radii. 

If  one  desires  to  employ  reagents,  the  highly  diluted  acetic 
acid  recommended  by  Kolliker  for  the  nerves  of  the  muscles 
(p.  363)  is  advisable  (Miiller  and  Saemisch).  Even  after  10-15 
minutes  the  epithelium  may  be  removed  with  the  forceps ;  while 
at  least  several  hours'  action  of  the  reagent  is  necessary  for  the 
examination  of  the  nerves.  The  action  of  very  dilute  chromic 
acid  (0.1-0.0 1  per  cent.),  to  which  0.25  per  cent,  of  chloride 
of  sodium  may  be  added,  is  also  advantageous,  at  least  with  the 
frog  (Kliline). 


Fig.  184.  The  cornea  of  the  rabbit  in  vertical  transverse  section,  after  treatment  with  chloride 
of  gold,  a,  the  older.  &,  the  young  epithelial  cells  of  the  anterior  surface  ;  c,  corneal  tissue  ;  d,  a 
nerve-branch ;  e,  finest  primitive  fibres ;  /,  their  distribution  and  termination  in  the  epithelium. 

To  recognize  the  penetration  of  the  (extremely  fine)  nerve- 
fibres  into  the  epithelium  of  the  conjunctiva,  and  thus  to 
verify  Cohnheim's  beautiful  discovery,  one  should  resort  to 
chloride  of  gold  (p.  163)  and  use  the  eyes  of  Guinea-pigs  and 
rabbits  (fig.  184).  The  frog's  cornea  shows  its  epithelial  nerve- 
distribution  even  without  any  reagents,  by  simply  remaining  in 
the  moist  chamber  (Engelniann). 


368 


SECTION   FIFTEENTH. 


"We  thus  become  acquainted  in  the  most  certain  manner  with 
the  penetration  and  termination  of  the  finest  nerve-fibres  in  an 
epithelial  layer. 

Many  additional  observations  of  a  relative  nature  have  been 
made  in  modern  times. 

Thus,  Hensen  informs  us  that  in  the  tail  of  the  frog's  larva 
he  saw  the  terminal  branches  of  the  cutaneous  nerves  termi- 
nate in  the  form  of  infinitely  fine  filaments  in  the  nucleoli  of 
the  epidermoid  cells.  Lipmann  recently  asserted  the  same  with 
regard  to  the  pavement  epithelium  of  the  posterior  surface  of  the 
frog's  cornea.  He  employed  the  chloride  of  gold.  These  obser- 
vations (which  would  prove  a  parallel  case  with  the  contractile 

fibre-cells)  still  await  confirmation. 
Langerhans — again  with  the  help 
of  the  gold  method — found  that  in 
the  human  cutis  branches  of  pale 
nerve-fibres  penetrate  between  the 
cells  of  the  rete  Malpighii ;  here 
they  probably  enter  small  radiated 
cells,  the  ascending  processes  of 
which  are  said  to  terminate  with 
slight  enlargements  beneath  the 
stratum  corneum. 

To  obtain  the  first  view  of  the 
numerous  nerves  of  the  dental 
pulp,  one  of  the  large  incisor  teeth 
of  the  rabbit  is  to  be  crushed  and 
the  examination  made  in  iodine 
serum.  The  finest  terminal  fibrillse 
(which  probably  penetrate  a  portion 
of  the  dental  tubes)  are  difficult  to 
examine.  Chloride  of  gold  and 
osmic  acid  are  of  no  service  (Boll). 
Solutions  of  chromic  acid  are  the 
most  useful. 

Disregarding  the  higher  nerves 
of  sense  at  present,  we  here  treat  only  of  the  so-called  terminal 
knobs,  the  tactile  and  the  Pacinian  bodies,  remarkable  terminal 


Fig.  185.  Terminal  knobs— 1,  from 
the  conjunctiva  of  the  calf. 

a,  knob ;  c,the  medullated  nerve-fibre, 
dividing  at  * ;  6,  its  pale  terminal  por- 
tion. 2,  from  man. 


MFSCLES    AND   NEKVES.  369 

structures  which  have  been  discovered  and  more  closely  inves- 
tigated within  the  last  few  years. 

The  terminal  knobs,  for  a  knowledge  of  which  we  are  in- 
debted to  Krause,  are  represented  by  the  drawing  fig.  185. 
In  marnmalial  animals,  as  it  is  known,  they  are  of  an  oval  form 
(1,  a),  while  in  man  they  are  more  globular  in  shape  (2,  a). 
They  belong  especially  to  certain  mucous  membranes,  although 
they  may  also  occur  in  the  external  integument. 

The  ocular  conjunctiva  is  to  be  selected  for  their  examina- 
tion, and  it  is  preferable  to  use  the  fresh,  warm  eye  of  an  an- 
imal, such  as  the  calf  or  hog,  that  has  just  been  slaughtered. 
Portions  of  the  conjunctiva  are  to  be  carefully  freed  from  the 
connective  tissue  which  lies  beneath  it,  and  examined  with- 
out any  fluid  media.  With  a  little  perseverance,  the  structures 
in  question  may  be  recognized  in  the  connective  tissue  by  their 
bright  appearance.  An  examination  of  this  kind  always  pre- 
sents difficulties,  however. 

Krause  has  made  us  acquainted  with  a  good  accessory,  which 
is  to  be  especially  employed  with  organs  which  are  no  longer 
fresh,  and  may  therefore  be  used  with  those  of  man.  This 
consists  in  an  immersion  in  ordinary  vinegar,  continuing  for 
several  days  or  a  week.  The  tissue  is  rendered  transparent,  and 
the  arrangement  of  the  nerves  may  be  observed  in  an  elegant 
manner.  Single  nerve-fibres  are  found  to  enter  the  terminal 
knobs  which  are  now  become  cloudy  and  have  dark  contours. 
The  pale  terminal  fibres  can  no  longer  be  perceived  by  this 
method,  however.  The  vinegar  may  be  replaced  by  dilute  acetic 
acid ;  a  mixture  of  acetic  acid  and  alcohol  also  renders  good 
service.  Finally,  tingeing  with  carmine  is  to  be  employed  with 
advantage. 

The  tactile  bodies  (fig.  186)  which  occur  in  certain  portions 
of  the  external  integument  (the  volar  surfaces  of  the  fingers 
and  toes,  the  palm  of  the  hand,  the  sole  of  the  foot,  etc.)  are 
embedded  in  a  part  of  the  sensitive  papillae  of  the  cutis,  and 
are  also  rather  difficult  objects  for  investigation.  Although, 
with  suitable  methods  of  treatment,  one  may  soon  recognize 
these  structures  and  become  convinced  of  their  connective-tissue 
nature,  and  likewise  that  the  oblong,  transversely  arranged 
24 


370 


SECTION   FIFTEENTH. 


bodies  on  their  surface  are  not  nervous  structures,  the  investi- 
gation of  the  end  of  the  nerve-fibre  still  presents  the  greatest 
difficulties. 

Various  methods  of  examination  have  been  employed  in  the 
investigation  of  the  tactile  bodies. 

The  freshest  possible  human  integument,  when  stretched, 


Fig.  186.    Two  nervous  papillae  from  the  volar  surface  of  the  index  finger,  with  the  tactile 
bodies  and  their  nerves. 


permits  of  quite  thin  vertical  sections  being  made  with  a  sharp 
knife.  These,  in  consequence  of  their  fibrillated  structure,  re- 
quire additional  measures  to  render  them  transparent.  There 
are  two  media  especially  which  are  used  for  this  purpose ;  a 
sometimes  more  concentrated,  sometimes  more  dilute  solution 
of  soda,  and  the  diluted  acetic  acid.  The  former  affords  quite 
handsome  but  also  very  perishable  specimens.  Thin  sections 
placed  in  a  watch-glass  swell  considerably  after  a  time,  and  then 
permit  the  epidermoidal  layer  to  be  removed.  Any  fragments 
of  the  rete  Malpighii  which  may  remain  are  to  be  removed 
by  brushing.  The  examination  is  to  be  made  with  a  strongly 
shaded  field,  and  also,  according  to  circumstances,  with  the  em- 
ployment of  a  drop  of  acetic  acid.  Other  investigators  have 
given  the  dilute  acetic  acid  entire  preference  over  the  solution 
of  soda,  and,  in  fact,  it  cannot  be  denied  that  many  details  of 
the  tactile  bodies,  and  especially  of  the  course  of  the  nerve  tc 


MUSCLES    AKD    NEKVES.  371 

and  in  the  same,  may  be  more  conveniently  brought  to  view  by 
means  of  this  reagent.  Such  sections,  tinged  with  carmine,  pre- 
sent handsome  appearances. 

Fresh  integument,  such  as  that  of  the  point  of  the  finger, 
may  likewise,  when  carefully  dried,  present  serviceable  views 
in  vertical  sections,  the  more  so  if  tingeing  with  carmine  is  also 
employed. '  Suitable  portions  of  the  integument  with  their 
natural  injection,  or  injected  with  Prussian  blue  and  treated  in 
this  manner,  are  adapted  for  distinguishing  the  two  kinds  of 
sensitive  papillae  of  the  skin  from  each  other.  Chromic  acid 
and  even  alcohol  preparations  occasionally  show  very  handsome 
tactile  bodies. 

Transverse  sections  of  the  papillary  bodies  of  the  skin,  hard- 
ened in  alcohol  or  chromic  acid,  tinged  with  carmine,  cannot 
be  dispensed  with. 

Gerlach,  years  ago,  made  us  acquainted  with  another  method. 
A  piece  of  integument  removed  from  the  volar  surface  of  the 
finger  is  to  be  placed  for  a  moment  in  hot,  and  then  in  nearly 
boiling  water.  The  epidermis  is  then  to  be  taken  off,  and  any 
portions  of  the  same  which  may  remain  are  to  be  removed  with 
a  brush.  The  piece  of  skin  is  then  to  be  hardened  for  several 
days  in  a  solution  of  the  chromate  of  potash.  Transverse  sec- 
tions are  now  to  be  made  from  the  papillae  with  a  razor,  and 
placed  in  water  under  the  microscope.  Strong  acetic  acid 
serves  to  render  them  transparent.  The  transverse  sections  of 
the  nerve-fibres  may  be  recognized  within  the  tactile  bodies. 
Injected  skin  is  to  be  used  in  order  to  avoid  confounding  them 
with  transversely  divided  capillary  vessels. 

All  these  methods  of  investigation  of  a  former  period  are 
unserviceable,  however,  when  the  termination  of  the  nerves  is 
concerned.  Here  the  freezing  method,  in  combination  with 
the  impregnation  with  metals,  such  as  chloride  of  gold,  osmic 
acid,  and  chloride  of  palladium,  promises  the  most. 

There  is  still  remaining  to  consider  the  remarkable  Pacinian 
or  Yaterian  body  (fig.  1ST),  the  most  complicated  form  of 
these  terminal  bodies  of  the  nerves  of  sensation. 

It  is  preferable  to  select  for  their  investigation  the  mesentery 
of  the  cat,  in  which  they  at  once  become  evident  to  the  eye,  and 


372 


SECTION    FIFTEENTH. 


are  isolated  by  slight  preparation.  By  the  application  of  indiffer- 
ent fluids  they  present  excellent  specimens,  in  which  the  struc- 
ture, the  concentric  capsules  (&). 
the  entering  nerve  (#),  with  the 
pale  terminal  filament  (c)  may 
be  readily  recognized.  Here, 
also,  the  latter  distinctly  shows  a 
combination  of  primitive,  or  axis- 
fibrillse,  as  was  ascertained  by 
Grandry  and  confirmed  by 
Schultze,  Michelson,  and  Ciac- 
cio.  Previous  injection  with 
cold-flowing  transparent  masses 
is  a  good  accessory ;  diluted 
acetic  acid  and  tingeing  may 
also  be  employed. 

Dilute  chromic  acid,  or  corre- 
sponding solutions  of  chromate 
of  potash,  may  likewise  be  em- 
ployed for  their  preservation  and 
examination.  I  find  the  acetic- 
pie  microscope  serve  for  the  detachment  of  the  capsules. 
Impregnation  with  silver  also  shows  on  these  the  familiar  mosaic. 
The  Pacinian  capsules  of  man  are  to  be  obtained  without 
much  trouble,  by  preparing  the  cutaneous  nerves  of  the  palm 
of  the  hand  and  the  sole  of  the  foot.  The  methods  of  investi- 
tigation  are  the  same  .as  for  those  of  the  cat. 

The  textural  conditions  of  the  nervous  system  in  the  foetus, 
and  the  history  of  the  origin  of  their  elements,  are,  as  yet,  by  no 
means  known  with  desirable  certainty.  The  embryos  of  our 
domestic  mammalia  or  of  the  hen,  which  have  been  immersed, 
as  fresh  as  possible,  in  dilute  solutions  of  chromic  acid,  or  of 
the  bichromate  of  potash,  and  slowly  hardened,  are  to  be  em- 
ployed. Transverse  sections  of  hardened  embryos  afford  very 
fine  review  preparations  for  the  spinal  cord,  the  spinal  ganglia, 
etc.  The  objects  tinged  with  carmine  are  to  be  mounted  in 
Canada  balsam. 


Fig.  187.  Pacinian  body  from  the  mes- 
entery of  a  cat.  a,  Nerve-fibre ;  6,  the 
capsules;  c,  the  pale-contoured  terminal 
filament  of  the  nerve-tube. 


MUSCLES   AND   NERVES.  373 

Many  characteristic  views  of  the  peripheral  nerves  of  the 
foetal  period  may  be  readily  obtained  in  the  fresh  larvae  of  the 
frog  and  salamander.  Together  with  the  nitrate  of  silver  and 
the  chloride  of  gold  treatment  (Eberth),  a  very  excellent  pro- 
cedure, given  by  Hensen,  may  also  be  employed.  The  larvae 
are  to  be  dipped  for  20-50  seconds  in  a  chromic  acid  solution  of 
from  3-4  per  cent.,  and  are  then  thrown,  still  living,  into  spring- 
water.  Then,  or  after  half  an  hour,  the  epithelium  may  be  re- 
moved from  their  tails  by  brushing.  Eberth  recommends  for 
the  same  purpose  to  place  the  frog's  larvae  for  a  half  or  a  whole 
hour  in  a  weak  solution  of  nitrate  of  silver  (1  gr.  to  5  ounces). 

In  consequence  of  the  extreme  delicacy  and  alterability  of 
these  tissues,  however,  the  most  conservative  methods  are  always 
the  best. 

Somewhat  more  strongly  hardened  embryos  afford  good  pre- 
parations relating  to  the  structural  conditions  of  the  developing 
spinal  cord  and  brain.  The  changes  in  form  of  the  former,  and 
also  of  the  spinal  ganglia,  with  a  progressing  development,  may 
be  readily  perceived.  Here,  also,  chromic  acid  and  bichromate 
of  potash  deserve  decided  preference  over  alcohol.  Transverse 
sections,  with  the  aid  of  carmine  tingeing,  suffice  for  the  first 
examinations. 

Concerning  the  tunics  of  the  central  organ,  it  is  better  to 
examine  the  arachnoid  and  pia  mater  fresh,  employing  the  re- 
agents which  are  customary  for  connective-tissue  parts. 

The  numerous  capillaries,  and  the  small  arterial  and  venous 
branches  which  are  associated  with  them,  cause  the  latter  mem- 
brane to  appear  very  well  adapted  for  the  study  of  the  vessels. 
In  suitable  specimens  (as  well  as  in  mechanically  isolated  ves- 
sels of  the  nerve-substance)  one  may  readily  recognize  that  the 
formation  of  tubercles  commences  in  the  adventitia.  It  was 
thought  that  the  rudimentary  cells,  which  are  found  here  (the 
so-called  vascular  nuclei),  increased  by  proliferation.  At  the 
present  time,  a  wandering  of  the  lymphoid  cells  of  the  blood 
into  the  surrounding  layer  has  become  more  probable.  If  sup- 
puration takes  place  in  the  pia  mater,  in  consequence  of  inflam- 
matory irritation,  the  emigration  of  the  lymph-cells  from  the 
blood-current  may  be  most  distinctly  recognized  (Bindfleisch). 


374  SECTION    FIFTEENTH. 

The  dura  mater  may  be  examined  fresh,  dried,  or  hardened 
by  means  of  chromic  acid, — methods  which  are  also  employed 
with  the  neurilemma  of  the  larger  nerves.  The  plexus  choroidei 
scarcely  requires  special  directions ;  its  injection  with  that  of 
the  brain  readily  succeeds.  Here  Miiller's  mixture  (p.  139) 
affords  good  preparations.  The  calcareous  concretions  of  the  t 
same,  the  so-called  brain-sand  (which,  as  is  known,  also  occurs 
in  the  human  pineal  gland),  are  to  be  studied  with  the  employ- 
ment of  acids  and  media  for  rendering  them  transparent,  espe- 
cially glycerine. 

The  pituitary  gland,  for  which  the  calf  is  to  be  especially 
recommended  (Peremeschko),  is  to  be  hardened  in  chromic 
acid,  Miiller's  fluid,  or  alcohol.  Thin  sections,  brushed  and 
tinged  with  carmine,  readily  yield  the  essential  appearances. 

We  have  already  noticed  above,  the  great  difficulties  which 
the  investigation  of  the  normal  textural  conditions  of  the  cen- 
tral organs  of  the  nervous  system  still  present.  Hence,  we  shall 
comprehend  that  their  numerous  pathological  alterations  are 
still  very  inadequately  known,  and  can  only  be  assailed,  histo- 
logically,  with  slight  results.  It  is  usually  accepted  that  the 
nervous  elements  indeed  undergo  numerous  secondary  processes 
of  degeneration,  such  especially  as  the  fatty,  and  also  amyloid 
and  colloid  transformations,  but  that  the  true  new  formations 
proceed  from  the  connective-tissue  framework  and  from  the 
vessels.  The  correctness  of  the  former  doctrine  has  more  re- 
cently, however,  become  doubtful,  and  the  lymphoid  migratory 
cells  exert  at  present  a  deep  and  disagreeable  influence  on  the 
latter.  The  finer  textural  conditions  of  the  framework  sub- 
stance are  also  uncommonly  difficult  to  follow,  as  the  very 
methods  of  hardening  which  are  customary  for  the  normal 
structure  frequently  render  very  little  service  in  the  domain  of 
pathology,  so  that  often  one  is  able  to  examine  only  fresh  ob- 
jects. For  connective-tissue  formations  one  should  try  very 
weak  chromic  acid,  according  to  Schulze  (p.  131),  likewise  Miil- 
ler's fluid,  diluted  with  about  an  equal  volume  of  water.  Fi- 
nally, the  skilful  employment  of  tingeing  methods  will  afford 
much  additional  assistance. 

Good  review  preparations  are  not  unf requently  afforded  by  a 


MUSCLES   AND    NERVES.  375 

method  practised  by  Billroth, — placing  small  pieces  of  brain  and 
spinal  cord  in  powdered  carbonate  of  potash  or  chloride  of  cal- 
cium for  24  hours.  By  this  means  the  objects  usually  gain  a 
degree  of  consistence,  which  permits  of  fine  sections  being 
made  ;  these  are  to  be  examined  in  water  (or  with  the  addition 
of  glycerine). 

To  investigate  the  fatty  degeneration  of  the  nerve-fibres,  as  well 
as  the  textural  changes  which  occur  in  the  peripheral  portion 
of  a  divided  nerve,  the  animal  which  has  been  subjected  to  the 
above  operation  is  to  be  examined,  after  the  proper  interval  of 
time,  either  quite  fresh  or  with  the  employment  of  the  solutions 
of  free  chromic  acid  and  of  bichromate  of  potash,  which  have 
been  recommended  for  the  spinal  cord  and  brain.  This  is  one 
of  the  few  structural  changes  of  the  nervous  apparatus  which 
present  but  slight  difficulties  to  the  practised  observer. 


0ection  0i*teentl). 

VESSELS  AND   GLANDS. 

THE  methods  of  investigating  the  vessels  differ  somewhat 
according  as  the  contained  mass  consists  of  blood  or  of  lymph  ; 
furthermore,  they  vary  considerably  in  proportion  to  the  size  of 
the  vessels.  One  variety  of  accessories  is  therefore  necessary 
in  the  examination  of  the  capillaries  and  small  vessels ;  others 
are  required  for  the  investigation  of  the  larger  and  largest 
trunks. 

The  finest  canals  of  the  blood-passages  are,  as  is  known,  the 
capillaries  (fig.  188,  A  j5),  which  are  very  thin,  nucleated, 
branched  membranous  tubes.  The  narrowest  capillaries  (A.  a 
J  B  a),  which,  however,  do  not  occur  in  all  parts  of  the  human 
body,  are  only  sufficiently  wide  to  allow  of  the  passage  of  the 
blood-cells  singly,  one  after  the  other.  A  similar  condition 
recurs  in  the  several  groups  of  vertebrated  animals,  modified, 
naturally,  by  the  size  of  the  blood-corpuscles.  Frogs  and 
naked  amphibise  have  therefore  capillaries  of  much  more 
considerable  diameter  than  are  met  with  in  the  human  body, 
and  the  capillaries  of  these  creatures  are  consequently  better 
adapted  for  many  investigations  than  our  own. 

Until  recently  the  purport  of  the  almost  universally  accepted 
history  of  the  development  of  the  capillary  vessels  was  that 
they  originated  in  the  blending  of  the  formative  cells  which, 
corning  together  in  a  single  row,  opened  into  each  other,  so  that 
the  cell-cavities  became  united  into  a  capillary  tube,  the  mem- 
branes of  the  cells  were  transformed  into  the  wall  of  the  vessel, 
and  the  persisting  nuclei  into  the  nuclear  formations  of  the 
latter. 

It  has  been  ascertained  by  the  concurrent  investigations  of 
several  observers  (Hoyer,  Auerbach,  Eberth,  and  Aeby)  that  the 
walls  of  the  capillary  vessels  are  not  in  reality  structureless,  but 


VESSELS   AND    GLANDS. 


377 


rather  that  they  are  formed  by  the  melting  together  of  very 
thin  and  flat  nucleated  cells  (the  cavity  of  the  capillary  is 
therefore  an  intercellular  passage).  The  boundary-lines  of 
these  cells  are  only  to  be  rendered  visible  by  means  of  impreg- 
nation with  silver,  and  were  previously  entirely  overlooked. 


Fig.  188.  Small  vessels  from  the  pia  mater  of  the  human  brain.  A,  a.  vessel  whose  trunk 
acquires,  at  the  lower  part,  d,  a  double  membrane,  and  at  its  upper  part  passes  over  into  two  fine 
capillaries,  a  and  6  ;  B. ,  a  second  one  ;  C',  a  somewhat  larger  trunk  with  a  double  membrane,  the 
inner  one,  a.  with  longitudinal  nuclei,  and  the  external  one,  6,  in  the  central  portions  of  which 
transverse  nuclear  formations  may  be  recognized. 

This  important  discovery  may  be  readily  verified  (figs.  189 
and  190).  A  frog,  a  mouse,  or  a  Guinea-pig  is  to  be  allowed 
to  bleed  to  death,  and  then  a  0.25  per  cent,  solution  of  silver  is 
to  be  injected  into  the  vessels.  The  simple  immersion  of 
organs,  such  as  the  retina  or  pia  mater  of  mammalial  animals 
or  of  man,  which  are  deprived  of  their  blood,  also  leads  to  the 


378 


SECTION    SIXTEENTH. 


desired  result.     The  object  is  to  be  washed  in  spring  water  and 
examined  in  acidulated  glycerine. 

More  recently  increased  attention  has  been  paid  to  a  some- 
what more  complicated  arrangement  of  the  capillaries  which 
occurs  in  the  lymphoid  organs,  the  lymphatic  glands,  the  Peye- 


Fig.189.    Capillary  network  from  // /    \^\  Fl,f\191;      Capillary  vessels  and 

the  lung  of  the  frog,  treated  with  a  If  I       W\       sma11  trunks  of  fthe  mammalia  ;  a, 

Bolution  of  nitrate  of  silver ;  Z>,  vas-  R9         \\     capillary  vessel  from  the  brain  ;  6, 

cular  cells:  a,  their  nuclei.  /)  /  \ \\    from  a  lymphatic  gland ;  c,  a  some- 

x  '  x  what  larger  trunk  with  a  lymphatic 
Bheath  from  the  small  intestine  ;  and 
d,  transverse  section  of  a  small  ar- 
tery of  a  lymphatic  gland. 

Fig.  190.    Capillary  vessel  from  the  mesenterium  of  the  Guinea-pig,  after  the  action  of  a  solu- 
tion of  nitrate  of  silver,    a,  vascular  cells ;  6,  their  nuclei. 

rian  and  solitary  follicles,  the  tonsils,  Malpighian  bodies  of  the 
spleen,  the  thymus  gland,  and  also  in  other  glands.  It  consists 
in  the  spreading  out  of  the  reticular  connective  tissue  of  these 
organs,  in  the  form  of  a  membrane,  around  the  primary  walls 
of  the  capillaries,  and  thus  forming  a  second  accessory  layer,  a 
so-called  adventitia  capillaris.  This  may  be  represented  by  fig. 
191,  J.  Furthermore,  microscopic  vascular  trunks  may  be  sur- 
rounded, with  a  larger  intervening  space,  by  a  connective-tissue 
sheath  (a)  whereby  the  cavity  which  is  thus  formed  (lymph- 
sheath)  serves  for  the  current  of  the  lymph  (c). 

There  are  by  no  means  many  organs  which  are  adapted  for 
the  primary  examination  of  the  capillary  vessels  of  man  and  the 
mammalia.  The  most  suitable,  and  therefore,  also,  the  most 
generally  recommended,  appear  to  be  the  brain,  the  pia  mater 


VESSELS    AND    GLANDS.  379 

of  the  same,  the  retina  of  the  adult  body,  and  the  lymphoid 
organs. 

To  obtain  characteristic  views  from  the  former  parts  a  small 
blood-vessel  which  is  barely  visible  in  the  gray  substance  is  to 
be  seized  and  an  attempt  made  to  remove  it  by  traction.  It  is 
then  to  be  placed  in  water  and  freed  from  any  adherent  brain- 
matter  by  means  of  the  wash-bottle,  or,  still  better,  by  brushing. 
In  this  way  will  be  perceived  a  trunk  with  abundant  ramifica- 
tions and  numerous  capillaries  as  terminal  branches,  and  not 
only  these  finest  forms  of  vessels  may  be  studied,  but  also  a  se- 
ries of  transformations  into  more  complicated  vessels.  The  pi  a 
mater  when  picked  also  affords  excellent  objects,  especially  if 
portions  be  selected  which  pass  over  a  furrow  between  the  con- 
volutions of  the  brain.  The  capillaries  of  the  retina  are  to  be 
treated  in  the  same  manner  as  those  of  the  brain-substance. 

The  organs  belonging  to  the  lymphatic  system  require  some- 
what greater  preparations  for  the  investigation  of  their  capilla- 
ries. Either  none  at  all  or  only  extremely  unsatisfactory  views 
are  to  be  obtained  from  the  fresh  parts.  For  this  reason,  prepa- 
ratory hardening  methods  (chromic  acid,  alcohol,  etc.)  are  to  be 
first  employed.  Thin  sections  from  the  tissue  which  has  be- 
come more  resistant  must  then  be  freed  from  the  innumerable 
lymph-corpuscles  .which  fill  the  connective-tissue  network 
before  the  desired  delicate  capillaries  can  be  brought  to 
view. 

Any  ordinary  preparation  serves  for  the  recognition  of  the 
nuclei.  These  are  rendered  sharper  by  dilute  acetic  acid,  like- 
wise by  carmine  tingeing,  which,  together  with  staining  with 
hsematoxyline  and  aniline  blue,  deserves  recommendation. 
Chloride  of  gold  also  affords  serviceable  specimens. 

In  organs  with  a  fibrous  structure,  even  where  there  is  a  consid- 
erable vascularity,  we  may,  as  a  rule,  search  in  vain  for  capilla- 
ries except  we  employ  especial  accessories  for  rendering  them 
prominent.  The  empty  capillaries  disappear  most  completely  in 
the  fibrillary  tissues.  The  familiar  action  of  acetic  acid  may  here 
be  made  use  of,  or,  which  is  to  be  preferred,  the  preparation 
may  be  first  colored  with  carmine  and  then  subsequently  ex- 
posed to  the  action  of  the  acid.  Glandular  organs,  on  the  con- 


380  SECTION   SIXTEENTH. 

trary,  require  the  application  of  alkalies  if  the  capillaries  are  to 
be  rendered  prominent  after  the  dissolution  of  their  cells. 

After  what  has  just  been  mentioned  it  is  unnecessary  to  dis- 
cuss further  the  great  value  of  transparent  injections  with  Prus- 
sian blue  or  carmine  for  rendering  the  capillary  and  larger 
vessels  of  an  organ  visible  ;  the  silver  solution  (p.  186)  may  also 
be  used  with  advantage.  The  slight  trouble  of  injecting  should, 
in  fact,  never  be  shunned  in  such  investigations,  as  the  struc- 
tural relations  of  all  organs  are  usually  rendered  much  more 
comprehensible  as  soon  as  the  distended  capillaries  have  afforded 
a  landmark  for  the  eye. 

"Where  it  is  possible  to  retain  the  blood  in  a  vascular  district, 
such  natural  injections  may  replace  the  artificial  ones,  but  the 
preparations  should  not  be  moistened  with  water. 

If  a  frog  or  a  salamander  be  at  hand,  the  capillaries  of  cer- 
tain parts  of  the,  body  may  be  examined  with  advantage  for 
comparison  with  the  human  textural  condition.  From  the  first 
animal  (preferably  killed  by  means  of  ether  or  chloroform)  the 
lower  eyelid  or  one  of  the  flat,  transparent  muscles  which  we 
have  mentioned  above,  p.  361,  is  to  be  taken.  The  membrana 
hyaloidea  also  affords  magnificent  views. 

The  larger  blood-vessels  wrhich  follow  these  no  longer  show 
the  original  simplicity  of  structure  possessed  by  the  capillaries. 
First  appears  the  original  capillary  membrane  (fig.  188  C)  meta- 
morphosed with  cells  and  longitudinally  arranged  nuclei  (a) ; 
then  a  second  layer  with  transversely  arranged  smooth  muscu- 
lar elements  scattered  through  it,  the  nuclei  of  which  are  seen 
at  b.  This  is  the  earliest  appearance  of  a  tunica  media  seu 
muscularis,  to  which  in  vessels  of  a  somewhat  larger  calibre  is 
gradually  associated  the  tunica  cellulosa,  the  external  connec- 
tive-tissue layer.  In  other  vessels  the  epithelial  tube  is  seen  to 
be  surrounded  by  an  elastic  inner  membrane  ;  this  is  the  first 
appearance  of  the  tunica  serosa.  "We  meet  with  other  trunks 
(and  these  have  for  the  most  part  the  character  of  venous  tubes) 
which  present  the  most  internal  cellular  layer,  the  elastic  inner 
membrane,  and  the  adventitia ;  but,  on  the  contrary,  no  trace 
of  any  muscular  middle  layer  can  be  recognized  in  them.  A 
complete  contrast  is  presented  by  the  arterial  trunks  (fig.  192), 


VESSELS   AND    GLANDS.  381 

the  muscular  middle  layers  of  which  are  very  strongly  devel- 
oped, and  its  contractile  fibre-cells  are  found  packed  closely 
together. 

The  methods  for  investigating  these  vessels  are  the  same  as 


Fig.  192.  A  email  arterial  trunk  without  an  epithelial  covering ;  Z>.  the  homogeneous  elastic 
internal  layer;  c,  the  middle  layer,  consisting  of  transversely  arranged  fibre  cells;  d,  the  external 
connective-tissue  covering.  , 

for  the  capillaries.  Even  the  localities,  such  as  the  substance 
of  the  brain,  the  pia  mater,  and  the  lymphoid  organs  frequently 
remain  the  same.  Together  with  these  the  mesenteric  arteries 
may  also  be  used  with  advantage.  Advantageous  use  may  be 
made  of  tingeing  methods,  especially  of  carmine  tingeing  with 
the  subsequent  action  of  acetic  acid,  and  also  of  dilute  acids 
and  alkalies.  Transparent  injections  are  very  useful  here, 
especially  for  estimating  the  extremely  variable  thickness  of 
the  walls  of  small  venous  and  arterial  branches. 

The  epithelium  in  somewhat  larger  trunks  is  to  be  examined 
in  part  in  fresh,  unaltered  specimens,  or  by  means  of  carmine 
tingeing  and  silver  impregnation  (see  page  160). 

Tingeing  with  carmine,  the  application  of  potash  solutions  of 
30-35  per  cent.,  and  of  20  per  cent,  nitric  acid  are  to  be  recom- 
mended for  the  recognition  of  the  muscular  layer.  The  action 


382  SECTION   SIXTEENTH. 

of  nitrate  of  silver  may  also  be  employed  for  rendering  visible 
the  contours  of  the  individual  contractile  fibre-cells. 

The  usefulness  of  still  another  method  here  makes  itself  felt, 
wlrch  is  of  unsupersedable  importance  in  the  examination  of 
larger  and  the  largest  vessels — we  refer  to  the  preparation  of 
thin  sections  through  their  walls.  Drying  was  formerly  em- 
ployed for  this  purpose.  At  the  present  time  the  embedding 
method  (p.  117)  has  taken  its  place. 

Preparations  hardened  in  alcohol  or  chromic  acid  also  afford 
handsome  sections  of  such  vessels  (fig.  191  d).  Beale  distends 
such  arterial  and  venous  trunks  as  much  as  possible  by  the 
energetic  injection  of  uncolored  gelatine,  and  then  makes  fine 
sections  through  the  hardened  mass.  He  recommends  this 
method  very  properly,  especially  for  the  demonstration  of  the 
contractile  fibre-cells.  We  recommend  for  this  purpose  espe- 
cially the  Malpighian  bodies  of  the  spleen,  the  follicles  of  the 
lymphatic  glands  and  of  the  kidney,  whereby  the  slight  trouble 
of  a  careful  brushing  should  not  be  avoided. 

Yessels  whose  walls  can  no  longer  be  seen  in  their  totality 
with  the  microscope  require  the  preparation  of  thin,  partly 
longitudinal,  partly  transverse  sections.  The  fresh  vessel  may, 
without  further  treatment,  be  dried  or  embedded,  and  then  ex- 
amined with  the  application  of  acids  and  alkalies,  or  it  may  be 
previously  boiled  in  vinegar  or  dilute  acetic  acid.  The  action 
of  20  per  cent,  nitric  acid,  likewise  Schulze's  treatment  with 
chloride  of  palladium,  and  the  subsequent  tingeing  with  carmine, 
as  also  Schwarze's  double  tingeing  with  carmine  and  picric  acid 
(p.  159)  deserve  to  be  recommended. 

The  various  strata  of  elastic  membranes,  connective  tissue, 
and  muscular  layers  are  thus  rendered  most  distinctly  visible. 
The  best  views  are  obtained  of  the  development  of  the  muscular 
layers  in  arteries  and  veins  of  medium  size,  and  of  the  retro- 
gression of  this  tissue  in  the  largest  vessels.  It  will  frequently 
be  found  that  the  epithelium  is  no  longer  preserved. 

A  second,  and  indeed  older  procedure,  consists  in  opening  a 
vessel  while  it  is  in  a  moist  condition,  and  then  with  the  scalpel 
and  forceps  separating,  under  water,  the  individual  layers  suc- 
cessively from  within  outwards,  or  from  without  inwards,  to  study 


VESSELS   AND    GLANDS.  383 

them  with  the  application  of  suitable  media.  By  scraping  the 
fresh  specimen  with  the  blade  of  a  scalpel,  larger  or  smaller 
shreds  of  the  epithelial  covering  may  be  readily  brought  to 
view.  The  free  border  of  the  valve  of  a  vessel  not  unfrequently 
presents  a  fine  view  of  this  covering,  and,  at  the  same  time,  a 
good  means  of  measuring  the  slight  thickness  of  the  same. 

For  the  recognition  of  the  vascular  nerves,  a  network  of  very 
fine  pale  filaments,  which  occupies  the  tunica  media  and  the 
contiguous  portions  of  the  external  layer,  select  the  mesentery  of 
a  frog,  treat  it  with  dilute  acetic  acid,  and  remove  the  epithe- 
lium by  brushing  (His). 

The  arrangement  of  the  various  capillary  districts  according 
to  the  magnitude  and  manner  of  distribution  of  the  vessels,  as 
well  as  the  size  of  the  tissue-spaces  surrounded  by  the  meshes 
of  the  network,  has  occupied  the  attention  of  anatomists  and 
physiologists  for  a  long  time.  Even  the  charming  appearances 
which  successful  preparations  of  this  kind  unfold  under  the 
microscope  must  exert  an  attractive  influence.  Then  it  is  only 
by  the  vascularity  of  an  organ  that  a  conclusion  can  be  made 
as  to  the  quantity  of  matter  which  it  assimilates,  either  in  its 
own  interest  or  for  the  service  of  other  organs  (glands).  The 
relative  arrangement  of  the  capillaries  is  of  great  importance 
in  the  mechanism  of  the  circulation. 

As  the  technology  of  injection  has  already  been  mentioned 
in  detail  in  a  previous  section  (p.  169),  we  may  simply  refer  to 
the  same.  For  the  study  of  the  capillaries,  as  has  been  already 
remarked,  one  should  only  examine  objects  injected  with  trans- 
parent masses  in  a  moist  condition  (either  quite  fresh  or  after 
a  short  immersion  in  alcohol,  and  then  with  a  subsequent  addi- 
tion of  glycerine),  as  opaque  masses  conceal  too  much,  and  all 
dry  preparations  present  a  distorted  appearance.  The  simple 
injecting  fluids  (the  cold  flowing  Prussian  blue  of  Beale  or  of 
Richardson,  see  p.  183,  184)  will  suffice  for  most  of  the  inves- 
tigations of  the  capillary  networks.  If  one  desires  to  employ 
a  double  injection,  Beale's  carmine  mixture  (p.  185)  may  be 
added. 

It  would  lead  us  beyond  the  limits  of  this  little  work  were 
we  to  mention  here  more  fully  the  various  appearances  of  the 


384 


SECTION   SIXTEENTH. 


capillary  network  according  to  the  size  of  the  vessels  and 
meshes,  as  well  as  the  form  of  their  arrangement.  A  few  re- 
marks may  therefore  be  sufficient,  and  the  text-books  on  his- 
tology recommended  for  further  instruction. 

Many  parts  of  the  body,  as  is  known,  remain  entirely  with- 
out vessels ;  others  are  but  slightly  vascular,  and  are  only  perme- 
ated at  considerable  distances  by  capillary  vessels ;  while  in  the 


Fig.  193.  Vessels  of 
the  voluntary,  transverse- 
ly striated  muscle,  a,  ar- 
terial ;  6,  venous  branch ; 
c,  the  straight  capillary 
network. 


Fig.  194.  Vessels  from  a  vertical  section  of 
the  mucous  membrane  of  the  stomach  ;  the 
fine  arterial  branch  divides  into  a  straight 
capillary  network,  which  forms  circular 
meshes  at  the  surface  of  the  mucous  mem- 
brane, and  passes  over  into  the  thick  venous 
trunk. 


extremely  vascular  organs  the  capillaries  are  closely  approxi- 
mated to  each  other,  and  the  meshes  are  smaller. 

The  anatomists  have  distinguished  two  fundamental  forms 
of  capillary  networks,  according  to  the  shape  of  the  parenchy- 


VESSELS    AND    GLANDS. 


385 


matous  spaces  surrounded  by  them  ;  namely,  1,  the  straight,  and 
2,  the  circular  network. 

Both  forms  arrange  themselves  according  to  the  shape  of  the 
tissue-elements.  Circular  parts  formed  of  cells  or  gland- vesicles 
have  a  similar  shaped,  that  is,  circular  network  of  vessels ;  while 
those  with  a  decided  fibrous  disposition,  or  parts  formed  of 
glandular  passages  and  tubes  running  in  a  parallel  direction, 
present  the  straight  capillary  network. 

Fig.  193  shows  the  straight  capillary  network  of  the  trans- 
versely striated  muscle  ;  fig.  194  the  same  of  the  mucous  mem- 
brane of  the  stomach  surrounding  the  gastric  glands.  The 
latter  assumes  the  form  of  a  circular  network  at  the  surface  of 
the  mucous  membrane,  where  the  gland-ducts  terminate  with 
round  apertures. 

"We  have  already  in  a  previous  section  (p.  273)  learned  that 


Kg.  195.  Vessels  of  the  fat-cells.    A.  Arterial  (a)  and  venous  (6)  branches,  with  the  capillaries 
between  them.     B,  the  capillaries  around  three  cells. 


the  lobules  of  fat-tissue  consist  of  groups  of  large  globular 
cells.  The  capillary  network,  fig.  195,  is  in  accordance  there- 
with. A  likewise  more  circular,  but  large-meshed  and  pecu- 
liarly formed  network  of  capillaries  is  seen  in  the  inner  layer 
of  the  retina  (fig.  196).  Where  small  papillary  projections 
appear  (external  integument  and  many  mucous  membranes), 

we  meet  with  simple  capillary  loops  (fig.  197);  where  these  are 
25 


386 


SECTION    SIXTEENTH. 


larger,  with  a  looped  network,  as  in  the  intestinal  villi.  The 
arrangement  of  the  capillary  networks  of  the  human  organism 
is  frequently  of  such  a  peculiar  nature  that  the  practised 


I  - 


...  a, 


Fig.  196.  Vessels  of  the  human  retina,  a,  arterial,  c,  venous  branch ;  Z>,  the  capillaries. 

observer  can  readily  recognize,  with  the  greatest  certainty,  from 
what  part  of  the  body  the  preparation  is  obtained. 


Fig.  197.  Capillary  loops  of  the  papillee  of  the  skin  (in  others  appear  the  tactile  bodies). 

The  first  appearance  of  the  vessels  in  the  embryo,  as  well  as 
the  subsequent  formation  and  transformation  of  the  foetal 
vessels,  constitute,  as  is  known,  a  very  difficult  and  therefore 


VESSELS    AND    GLANDS.  387 

still  to  a  great  extent  deficient  section  of  histology.  The  more 
recent  discoveries  concerning  the  structure  of  the  walls  of 
the  capillaries  also  make  a  revision  of  the  earlier  statements 
urgently  necessary. 

Very  young  embryos  of  birds,  mammalia,  and  fishes  are  to 
be  recommended  for  the  investigation  of  the  origin  of  vessels. 
Among  these,  the  embryos  of  the  hen  have  been  employed  for 
many  years  and  stand  in  the  first  line,  in  consequence  of  the 
facility  with  which  suitable  material  may  be  obtained.  The 
formation  of  the  first  capillary  reticulation  may  be  observed 
in  the  area  vasculosa  from  the  end  of  the  first  and  on  the 
second  day  of  incubation.  For  this  purpose,  the  germinal 
membrane  is  to  be  cut  out  beneath  the  surface  of  lukewarm 
water  to  which  a  little  chloride  of  sodium  and  albumen  has 
been  added.  It  is  then  to  be  examined  either  quite  fresh  with 
the  application  of  an  indifferent  fluid,  or  of  a  strongly  diluted 
solution  of  chromic  acid  ;  or,  which  is  to  be  considered  as  more 
advantageous  for  many  purposes,  after  having  been  hardened 
in  chromic  acid  or  bichromate  of  potash,  it  is  to  be  investigated 
with  the  aid  of  glycerine  and  tingeing  methods. 

In  order  to  follow  the  further  peripheral  formations  of  vessels 
one  may  use  the  embryos  of  the  hen  at  a  more  advanced  stage, 
for  example,  their  allantois ;  or  the  embryos  of  mammalia  may 
be  employed.  In  the  latter,  the  urinary  sac,  the  membraua 
capsulo-pupillaris  and  hyaloidea  of  the  eye  also  afford  admir- 
able preparations. 

A  very  convenient  object  for  examination  is  presented  during 
the  early  part  of  the  summer  by  the  tail  of  the  frog's  larva. 
As  the  living  animal  may  be  examined  either  on  the  Schulze's 
object-bearer  (p.  243),  or  by  means  of  a  strip  of  moist  blotting- 
paper  wrapped  round  its  body  without  injury,  and  again 
placed  in  the  reservoir,  it  is  possible  to  follow  from  day  to 
day,  in  one  and  the  same  specimen,  the  alterations  in  the  vascu- 
lar formations  which  take  place  in  accurately  designated  places. 
Further  assistance  is  afforded  by  brushing  off  the  epithelium, 
as  performed  by  Hensen  (p.  373).  The  application  of  a  dilute 
solution  of  nitrate  of  silver  promised  important  disclosures 
here.  It  has  presented  the  unexpected  result,  that  vascular 


388  SECTION   SIXTEENTH. 

cells  cannot  be  rendered  visible  in  developing  capillary  tubes 
(Kolliker,  Golubew).  Many  vascular  districts  of  adult  crea- 
tures, however,  behave  in  a  similar  manner ;  thus,  for  example, 
those  of  the  hyaloidea  of  the  frog  (Golubew)  and  of  the  mam- 
malial  liver  (Eberth).  Darkness,  therefore,  still  prevails. 

Pathological  changes  of  the  blood-vessels,  as  is  known,  are  met 
with  often  enough.  In  so  far  as  they  consist  of  a  metamor- 
phosis of  the  structure,  they  affect  the  larger  trunks,  especially 
of  the  arteries,  much  more  frequently  than  the  finest  arterial 
and  venous  terminal  branches,  or  the  capillaries  lying  between 
them. 

In  the  arterial  walls  of  older  persons  there  are  generally  found 
— increasing  in  frequency  with  the  advance  in  life — changes  of 
the  inner  vascular  membrane  in  the  form  of  smaller  or  larger 
whiter  or  yellower  spots  and  plates  projecting  somewhat  above 
the  surface.  These  are  found  by  the  microscopical  analysis  to 
consist  of  collections  of  fat-molecules.  There  may  afterwards 
be  a  softening  and  breaking  down  of  these  fatty  degenerated 
places. 

In  the  atheromatous  processes,  also,  we  again  meet  with  the 
same  fatty  deposits,  but  in  the  deeper  strata  of  the  intema  con- 
tiguous to  the  muscular  coats,  after  a  proliferating  thickening 
of  the  inner  coats  of  the  vessels  has  taken  place  as  a  result  of 
an  irritation.  Here,  also,  a  softening  of  the  fatty  infiltrated 
place  occurs,  and  the  melting  process  advances  at  the  expense 
of  the  remaining  layers  of  the  inner  coat  of  the  vessel.  When 
a  regular  atheromatous  pulp  (which  may  force  its  way  into  the 
blood-passage)  has  been  formed,  its  elements  are  shown  by 
microscopical  analysis  to  consist  of  fat-molecules,  isolated  or 
united  in  globular  conglomerations,  crystals  of  cholesterine,  and 
fragments  of  tissue.  These  thickened  places  in  the  intema 
may,  however,  undergo  still  another  degeneration,  a  hardening, 
which  may  also  be  combined  with  the  former ;  they  may  be- 
come calcified,  and  form  hard  plates  or  tablets  in  the  walls  of 
the  vessel. 

By  such  atheromatous  changes  in  the  arterial  walls  are  caused, 
at  least  to  a  great  extent,  arterial  aneurisms  which  in  part  per- 
mit of  the  recognition  of  all  three  of  the  groups  of  layers, 


VESSELS   AND    GLANDS.  389 

although  thickened  and  metamorphosed  in  part  after  the 
destruction  of  the  intema,  or  also  of  the  muscular  coat,  consist 
either  of  both  coats  or  of  the  connective-tissue  coat  alone,  which 
latter  then  presents  transformations,  thickenings  of  its  tissue, 
etc., — matters  which  we  cannot  consider  further  at  present. 

The  question  arises — How  are  such  abnormities  of  the  arterial 
walls  to  be  examined  ? 

In  general,  by  means  of  the  same  methods  with  which  we 
have  already  become  acquainted  in  the  examination  of  the  nor- 
mal structure.  By  pulling  off  the  individual  layers  from  the 
fresh  specimen,  then  on  horizontal  and  vertical  sections  of  the 
walls  after  hardening  in  alcohol  or  chromic  acid,  or  finally  by 
the  aid  of  the  embedding  and  drying  methods.  The  coats, 
boiled  in  vinegar  and  then  dried,  also  afford  handsome  sections 
whereby  the  fat-molecules  of  the  atheromatous  mass  make  their 
appearance  in  an  elegant  manner.  Atheromatous  pulp  is,  like 
pus,  etc.,  to  be  spread  out  with  water. 

The  method  of  examination  also  remains  the  same  for  the 
pathol6gical  metamorphoses  of  the  structure  of  the  veins.  As 
with  the  arteries,  we  here  omit  the  dilatations  of  the  veins,  and 
the  occlusions  from  thrombi  and  emboli  (that  is,  clots  which 
have  originated  in  a  remote  locality,  and,  carried  forward  by 
the  blood,  have  finally  become  wedged  into  a  vessel).  Only 
those  layers  of  the  walls  which  contain  vessels,  especially  the 
adventitia  and  the  middle  layer,  are  at  first  concerned  in  the 
inflammatory  processes  of  the  veins.  At  the  same  time  thero 
is  tumefaction,  the  formation  of  so-called  exudation  masses,  and 
an  accumulation  of  pus-corpuscles.  The  inner  coat,  which  is 
not  immediately  concerned  in  the  inflammatory  process,  is  also 
at  last,  as  a  result  of  these  structural  changes,  drawn  into  the 
sphere  of  the  process.  It  appears  cloudy,  thickened,  rough, 
and  may  become  separated  in  shreds. 

Such  rough  inner  surfaces  of  venous  as  well  as  arterial  ves- 
sels frequently  receive  aggregations  of  coagulated  fibrine  from 
the  blood.  Consequently  we  see  such  deposits  on  the  intema  of 
inflamed  veins,  as  well  as  on  softening  atheromatous  patches 
and  in  the -dilated  sacks  of  aneurismal  arteries. 

Pathological  changes  of  small  vessels,  microscopic  arteries 


390  SECTION   SIXTEENTH. 

and  veins,  escape  the  notice  of  the  physician  much  more  readily, 
as  will  be  appreciated,  and  also  cause  much  slighter  effects  dur- 
ing life. 

In  amyloid  degeneration  of  the  smaller  arteries  the  middle 
coat  is  seen  to  be  the  seat  of  the  deposit.  The  fibre-cells  of  the 
muscular  coat  lose  their  structure  and  become  transformed 
into  amyloid  flakes  ;  and  in  calcifications,  also,  the  deposit  of 
bone-earth  takes  place  in  this  contractile  element. 

The  small  arteries  of  the  brain-substance  occasionally  under- 
go an  interesting  metamorphosis.  In  vessels  of  extreme  minute- 
ness, up  to  those  of  0.5"'  in  diameter,  a  tearing  of  the  inner  and 
middle  coats  takes  place  ;  extravasated  blood  becomes  infiltrated 
under  and  into  the  adventitia,  and  arches  this  forward,  in  vari- 
ous ways,  into  vesicles  and  knobs.  If,  at  last,  the  external  con- 
nective-tissue layer  also  becomes  torn  through,  apoplectic  effu- 
sions occur.  Should  it  hold,  however,  a  striking  microscopic 
appearance  is  unfolded  in  the  gradual  metamorphosis  and 
breaking-down  of  the  extravasated  blood-corpuscles ;  so-called 
granule  cells,  aggregations  of  brown  and  yellow  pigment,  and 
their  final  dissolution  may  be  observed. 

Fine  microscopic  veins  and  their  branches,  which  are  passing 
over  into  capillaries,  occasionally  show  similar  varicosities  of 
their  lumen.  Although  with  the  above-mentioned  arteries  the 
bulging  is  caused  by  the  laceration  of  the  coats  and  the  extra- 
vasation of  the  blood,  here  all  three  of  the  coats  are  uninjured. 

Calcareous  and  fatty  degenerations,  and  likewise  deposits  of 
pigment,  have  been  noticed  in  the  capillaries  as  well  as  in  the 
smallest  arterial  and  venous  branches  which  are  associated  with 
them.  Furthermore,  emboli  of  the  same,  as  well  as  thicken- 
ings of  their  walls,  belong  to  the  more  interesting  occur- 
rences. 

Calcifications  have  thus  far  been  noticed  chiefly  in  the  capil- 
laries of  the  brain  ;  they  occur  very  rarely.  Much  more  fre- 
quently, especially  in  the  brain  of  older  persons,  fatty  degener- 
ations, groups  of  aggregations  of  small  fat-molecules  around  the 
nuclei  or  in  the  place  of  the  same,  are  noticed.  This  structural 
metamorphosis  is  occasionally  diffused,  in  the  most  extended 
manner,  throughout  a  whole  brain.  Deposits  of  black  pigment 


VESSELS   AND    GLANDS.  391 

molecules  have  been  observed  in  the  capillaries  of  the  spleen, 
liver,  and  also  of  the  brain,  in  melansemia. 

Peculiar  emboli  of  the  finest  arteries  and  veins  from  masses 
of  fluid  fat  have  also  been  noticed  more  recently  in  so-called 
pysemia  (E.  Wagner). 

We  have  already  mentioned  above  the  normal  occurrence  of 
the  adventitia  of  capillaries.  Something  of  the  kind  is  also  met 
with  under  abnormal  circumstances.  The  capillaries  of  a  part 
in  a  condition  of  inflammatory  irritation  gradually  receive  an 
aggregation  of  spindle-shaped  cells,  precisely  similar  to  those 
which  occur  in  the  normal  development.  Very  fine  appear- 
ances of  this  kind  may  be  obtained  from  the  inflamed  cornea. 
An  aggregation  of  this  undeveloped  connective-tissue  formation 
of  the  gelatinous  tissue  may  also  appear  as  an  adventitia  around 
capillaries  (Billroth). 

In  all  textural  changes  of  the  capillaries,  like  those  of  the 
larger  and  largest  trunks,  the  greatest  attention  is  to  be  paid  to 
the  nuclear  formation  of  the  so-called  vascular  cells,  as  it  is  just 
these  epithelioid  cells  which  rapidly  assume  a  condition  of 
luxurious  proliferation,  and  thus  give  rise  to  numerous  new 
formations  (Thiersch,  Waldeyer,  Bubnoff). 

The  structural  changes  which  have  thus  far  been  mentioned 
of  the  smaller  and  smallest  vessels  coincide  exactly  with  those 
of  the  normal  body  in  so  far  as  the  methods  necessary  for  their 
examination  are  concerned. 

A  matter  which  has  caused  numerous  controversies  is  the 
manner  in  which  the  origin  of  vessels  takes  place  under  patho- 
logical conditions. 

Such  productions  of  new  blood-vessels,  as  is  known,  are  not 
rare  occurrences,  and  appear  in  hypertrophied  organs,  in  neo- 
plasms, in  so  called  pseudo-membranes,  and  granulations.  Quite 
massive  new  formations  of  blood-vessels  may  be  recognized  in 
the  so-called  vascular  tumors.  Numerous  sack-  and  knob- 
shaped  expansions  of  the  dilated  capillaries  are  met  with  in  the 
capillary  telangiectasias,  especially  such  as  occur  in  the  skin. 
The  methods  for  examining  the  tissues  of  the  skin  must  here  be 
employed.  Preparations  boiled  in  vinegar  and  then  dried 
afford  characteristic  views.  ' 


392  SECTION   SIXTEENTH. 

When  such  newly  formed  vessels  are  examined  they  show 
either — and  this  is  generally  the  case — the  character  of  the 
capillaries  or  those  of  the  arteries  and  veins,  while  the  blood 
which  circulates  through  them  presents  nothing  especial.  Their 
diameters  are  either  those  of  the  normal  condition,  or  they  are 
increased  frequently  in  the  most  remarkable  manner.  At  the 
same  time  partial  dilatations  of  the  walls  frequently  occur.  Knob- 
shaped  pouches  are  also  met  with,  especially  in  vascular  tumors, 
which  require  more  accurate  investigations. 

At  a  former  period,  swayed  by  the  theory  of  spontaneous 
cell-formation  and  the  exudation  doctrine  of  that  time,  it  was 
frequently  asserted  that  these  pathological  vessels  (like  the 
blood  contained  in  them)  originated  independently  of  those  of 
the  neighboring  normal  tissue,  and  only  subsequently  became 
united  with  the  adjacent  vessels. 

At  the  present  day  we  may  say  that  this  theory  was  false, 
and  it  has  also  never  failed  to  be  frequently  attacked.  £u>  new 
formation  of  vessels  deviating  from  that  of  the  foetal  body 
occurs  in  the  domain  of  pathology.  In  both  cases  the  new  ves- 
sels arise  by  growth  from  the  existing  ones. 

According  to  more  accurate  investigations  which  have  been 
made,  the  formation  of  vessels  in  a  tumor,  like  a  so-called  pseu- 
do-membrane, appears  to  take  place  but  slowly  and  gradually, 
and  thus  to  form  a  striking  contrast  to  the  rapidity  with  which, 
for  instance,  an  aggregation  of  pus-cells  may  take  place. 

Either  the  fresh  tissue  or  that  hardened  in  alcohol,  chromic 
acid,  etc.,  is  to  be  employed  for  examination.  The  escape  of 
the  blood-corpuscles  from  the  newly  formed  vessels,  which 
readily  occurs  in  such  preparations,  is  a  very  unfortunate  cir- 
cumstance, and  is  responsible  to  a  considerable  extent  for  the 
scanty  results  which  so  many  investigators  have  obtained  in  this 
direction.  If  the  injection  with  transparent  masses,  which  is 
frequently  difficult,  it  is  true,  succeeds,  the  whole  naturally 
gains  extraordinarily  in  clearness.  Thus  Thiersch  made  the 
interesting  observation  in  the  healing  of  wounds  of  the  tongue, 
that  at  the  commencement  a  system  of  lacuna-like  passages  is 
formed  in  the  granulation-tissue  which  lead  from  the  loosened 
arterial  walls  to  similarly  constituted  veins.  The  largest  pro- 


VESSELS   AND    GLANDS.  393 

portion  of  these  "  plasmatic  "  canals  afterwards  disappear,  but 
a  portion  of  them  become  widened  and  form  blood-conveying 
vessels,  and  the  cells  of  their  walls  are  produced  by  the  adjacent 
tissues.  Inj  ections  are  an  indispensable  accessory  for  such  studies. 

The  lymphatics,  as  is  known,  show  in  their  large  trunks  a 
structure  reminding  us  of  that  of  the  veins,  and  also  coincide 
with  them  in  the  abundance  of  their  valves.  The  latter  also 
continue  in  the  fine  branches,  and  give  them  a  very  characteris- 
tic knotty  appearance.  So  long  as  such  a  constitution  can  be 
recognized  the  walls  of  these  tubes,  although  at  last  simplified 
to  a  structureless  membrane,  are  formed  of  a  special  tissue  which 
differs  from  the  neighboring  tissues. 

The  same  methods  are  employed  for  the  examination  of  the 
walls  of  these  vessels  as  for  the  arteries  and  veins.  Large 
trunks  may  be  dissected  out,  slit  up,  and  examined  by  pulling 
off  the  individual  layers,  or,  after  drying,  longitudinal  and  trans- 
verse sections  may  be  made.  It  is  best  to  inject  small  trunks 
with  pure  gelatine  by  tying  in  a  fine  canule ;  after  cooling,  thin 
transverse  sections  may  be  made.  The  finer  lymphatics  appear 
at  first  to  form  cavities  and  passages  surrounded  only  by  con- 
nective tissue.  By  the  application  of  the 
dilute  solution  of  nitrate  of  silver  (prefera- 
bly in  the  form  of  an  injection),  it  has  been 
ascertained,  however,  that  these  also  have  a 
wall  consisting  of  the  characteristic  vascular 
cells  (fig.  198,  a).  While  the  latter,  in  the 
capillaries  of  the  blood-passages,  however, 
usually  presents  a  certain  independence 
in  opposition  to  the  adjacent  tissues,  the 
walls  of  the  lymph-canals  are  intimately 

J       •  .    J          Fig.  198.  A  lymphatic  ca- 

blended   with  the  neighboring  connective    ™i  from  the  large  interne 

of  the  Guinea-pig,      a,  va»- 

tisSlie.  cular   ^U;    6>    intercalary 

plate. 

In  investigating  the  arrangement  of  the 

finer  lymphatics  of  an  organ,  the  injection  of  cold  flowing, 
transparent  masses  of  Prussian  blue  and  carmine  (see  above, 
p.  185)  is  to  be  employed,  together  with  the  subsequent 
hardening  in  alcohol.  In  doing  this  the  canule  is  either 
to  be  tied  in  or  the  method  by  puncture  is  to  be  used. 


394  SECTION    SIXTEENTH. 

The  injection  is  sometimes  easily  accomplished  in  some  parts  of 
the  body,  occasionally  only  with  the  greatest  difficulty. 

The  natural  injection,  which,  for  the  blood-vessels,  may 
afford  to  the  unpractised  a  substitute  for  the  artificial  injection 
is,  from  the  nature  of  the  enclosed  fluid,  of  very  limited  impor- 
tance for  the  lymphatics.  The  lymph  proper  disappears  as  a 
colorless  fluid  in  the  tissue  of  the  organ,  and  the  small  vessels 
only  glimmer  forth  from  the  tissue  where  a  pathological  color- 
ing matter,  of  the  bile  or  of  the  blood,  for  example,  is  retained 
and  mixed  with  the  lymph.  The  chyle,  on  the  contrary,  forms, 
as  is  known,  a  milk-white  fluid,  in  consequence  of  the  larger 
amount  of  fat  which  it  contains,  and  hence  its  vessels  are  seen 
distended  in  a  beautiful  manner.  Mammalial  animals,  espe- 
cially young  suckling  examples,  killed  during  the  digestion  of 
fat  (3-5  hours  after  its  reception)  afford,  therefore,  excellent 
objects  for  the  study  of  the  chyle  ducts  and  vessels,  a  subject  to 
which  we  shall  return  at  the  investigation  of  the  organs  of 
digestion. 

Pathological  new  formations  of  lymphatics,  especially  in  tu- 
mors, are  of  frequent  occurrence,  although  this  subject,  in  con- 
sequence of  the  difficulty  of  its  investigation,  still  represents 
almost  a  terra  incognita.  The  younger  Krause  has  lately  com- 
municated a  few  observations  concerning  them.  He  succeeded, 
in  scirrhus  and  medullary  sarcoma,  in  injecting  trunks  lying  in 
the  connective-tissue  bands  of  the  framework,  and  likewise 
large  vessels  in  myoma  of  the  labia.  May  these  experiments 
very  soon  be  further  extended ! 

The  structure  of  the  lymphatic  glands  has  recently  become 
considerably  more  comprehensible  from  the  labor  of  a  number 
of  observers. 

The  extreme  softness  and  the  opacity  of  the  fresh  organ, 
caused  by  the  presence  of  millions  of  lymph-corpuscles,  leads 
to  the  employment  of  hardening  methods  and  brushing. 

These  methods  are  the  customary  ones.  Immersion  in  alco- 
hol, at  first  in  such  as  is  ordinarily  used  for  preparations,  which 
has  been  diluted  with  about  half  its  volume  of  water,  leads  as  a 
rule,  in  from  5-8  days,  to  the  desired  object,  especially  if  the 
precaution  is  observed  to  change  the  fluid  frequently.  The 


VESSELS   AND    GLANDS.  395 

alcohol  finally  added  should  no  longer  become  cloudy.  If  a 
sufficient  consistence  is  not  obtained  in  this  manner,  stronger 
alcohol,  and  finally  that  which  is  almost  free  from  water  may 
be  used,  and  thus,  not  unf  requently  in  the  middle  or  towards 
the  end  of  the  second  week,  preparations  will  be  obtained  which 
are  suitable  for  sections  and  for  brushing.  Over-hardening  is, 
however,  to  be  most  carefully  avoided  if  the  framework  sub- 
stance is  to  be  examined,  while  strongly  indurated  alcoholic 
preparations  afford  the  best  specimens  for  the  investigation  of 
the  blood-  and  lymph-vessels  of  these  organs.  For  many  pur- 
poses chromic  acid  deserves  the  preference  to  alcohol.  Com- 
mence with  weak  solutions  and  proceed  very  gradually  to 
stronger  ones.  The  shrivelling  which  is  usually  connected  with 
alcoholic  preparations  may  thus  be  frequently  avoided  to  a  con- 
siderable degree.  Solutions  of  the  bichromate  of  potash  of  a 
corresponding  concentration  are  also  very  serviceable.  All 
lymphatic  glands  once  hardened  by  any  of  these  ways  may  be 
preserved  for  a  long  time  in  a  serviceable  condition,  and  may 
be  used  for  occasional  observations. 

Small,  fresh  lymphatic  glands  from  healthy  bodies  do  not  as 
a  rule  present  any  difficulties  in  hardening.  It  is  otherwise 
with  those  which  are  very  voluminous,  or  no  longer  fresh,  as 
well  as  with  those  which  are  affected  by  many  varieties  of 
degeneration.  Thus,  for  example,  typhus  mesenterial  glands 
require  much  care  as  a  rule,  and  the  object  is  not  always 
accomplished.  The  previous  injection  of  the  hardening  fluid 
through  the  blood  or  lymphatic  vessels  of  the  organ  to  be 
immersed  is  a  useful  accessory  with  such  organs  as  are  difficult 
to  manipulate.  Attempts  may  be  made  in  vain  to  harden  these 
very  glands  by  immersing  them  for  8-14  days  in  alcohol  of  in- 
creasing strength,  and  finally  in  that  which  is  almost  absolute, 
success  only  being  obtained  afterwards  by  placing  them  in 
chromic  acid  solutions. 

Toldt  has  recently  recommended  another  procedure  which 
permits  of  the  preparation  of  the  thinnest  sections,  and  thus 
renders  the  trouble  of  brushing  unnecessary  to  a  great  extent. 
The  fresh  glands  are  to  be  placed  for  3-4  days  in  very  "  dilute, 
wine-yellow  "  chromic  acid.  When  the  hardening  has  reached 


396  SECTION    SIXTEENTH. 

the  interior  it  is  to  be  placed  for  the  same  length  of  time  in 
glycerine  diluted  with  an  equal  part  of  distilled  water. 

It  would  appear  almost  superfluous  to  give  further  directions 
for  the  examination  of  the  framework  of  the  alveoli  or  follicles 
(fig.  199,  d)  and  lymphatic  vessels  (e).  The  glands  of  younger 
animals,  or  such  as  are  in  a  swollen  condition,  are  to  be  employed 
for  the  first  recognition  of  the  cellular  character  of  the  reticular 
tissue.  Among  the  tingeing  methods,  that  with  carmine  accom- 
plishes most  in  these  cases.  The  reagents  mentioned  at  the 
smooth  muscles  are  employed  for  the  recognition  of  the  fibres 
of  this  tissue  at  and  in  the  septa,  especially  the  treatment  with 
chloride  of  palladium  and  the  double  staining  with  picric  acid 
and  carmine  (p.  159). 


Fig.  199.  Section  through  one  of  the  smaller  lymphatic  glands,  with  the  current  of  the  lymph 
— half  diagrammatic  figure — «,  the  capsule  ;  6,  septa  between  the  alveoli  or  follicles  of  the  cor- 
tex (d)  ;  c,  system  of  septa  of  the  medullary  substance  as  far  as  the  hilus  of  the  organ ;  e,  lymph- 
tubes  of  the  medulla ;  /,  afferent  lymphatic  currents,  which  surround  the  follicles  and  flow 
through  the  spaces  of  the  medulla ;  ff,  union  of  the  latter  into  an  afferent  vessel  (h)  at  the  hilus 
of  the  organ. 

The  blood-vessels  may  be  injected  either  from  the  small  ar- 
terial branches  which  enter  the  gland  when  the  organ  is  suffi- 
ciently voluminous,  or,  in  smaller  glands,  by  the  neighboring 
large  trunks;  thus,  for  example,  the  pancreas  Asellii  of  the 
smaller  mammalia  may  be  injected  from  the  mesenteric  ar- 
teries and  the  portal  vein.  Here  the  double  injection  readily 
succeeds. 

A  few  years  ago  I  gave  more  accurate  directions  for  the  in- 
jection of  the  lymphatics  (/,  ^,  K)  by  the  afferent  and  efferent 


VESSELS    AND    GLANDS.  397 

lymphatic  vessels  of  the  glands.  In  these  cases,  as  a  rule,  find- 
ing the  lymphatics  usually  causes  greater  difficulty  than  the 
subsequent  manipulations. 

Transparent  and — as  I  will  add,  relying  on  recent  experience 
— cold-flowing  injection  masses  should  always  be  used.  But 
not  all  lymphatic  glands  are  adapted  for  injecting.  As  with 
all  injections  of  lymphatics,  fat  subjects  and  bodies  already 
commencing  to  decompose  are  to  be  avoided.  (Edematous 
portions  of  the  body  are  usually  best  qualified.  A  preparatory 
immersion  in  water  for  several  hours  may  also  prove  advanta- 
geous. 

If  a  mammalial  animal  be  employed,  the  following  procedure 
presents  the  greatest  advantages.  The  animal  is  to  be  killed 
by  a  blow  on  the  head,  or  by  strangulation.  The  ductus  thora- 
cicus  is  to  be  immediately  ligated  high  up,  and  the  body  allowed 
to  lie  for  2-6  hours.  After  this  interval  the  lymphatics  are, 
for  the  most  part,  firmly  distended,  and  neadily  permit  of  the 
injection  being  made  in  the  direction  in  which  their  valves 
open.  In  injecting  the  vasa  effereiitia,  on  the  contrary,  it  is 
difficult  to  overcome  the  resistance  of  the  valves,  and  it  only 
succeeds  in  isolated  cases. 

The  various  degrees  of  distention  are  here  of  great  impor- 
tance for  the  intelligibility  of  the  whole  current.  At  the  com- 
mencement, therefore,  only  injections  which  have  been  early 
discontinued  should  be  used,  proceeding  gradually  to  the  em- 
ployment of  those  which  have  been  more  prolonged.  The  in- 
jection of  a  second  or  even  third  lymphatic  gland  by  the  vasa 
efferentia  of  a  previously  injected  gland  affords  very  fine  speci- 
mens. 

It  has  already  been  remarked,  at  page  197,  that  Hyrtl  and 
Teichmann  have  facilitated  this  procedure  considerably  by 
means  of  the  puncturing  method ;  and  in  fact  this  process  ac- 
complishes a  great  deal  for  the  lymphatic  glands.  Fine  tubes, 
cautiously  introduced  beneath  the  capsules  of  larger  and  smaller 
glands,  as  a  rule,  readily  fill  the  investing  spaces  of  the  follicles, 
and  from  these  the  passages  of  the  medullary  substance.  This 
method  is  indeed  inestimable  for  the  examination  of  the 
passages  of  pathologically  metamorphosed  lymphatic  glands. 


398  SECTION    SIXTEENTH. 

It  may  be  practised  with  the  syringe  or  with  the  constant 
pressure. 

True  glands,  belonging  in  the  narrower  sense  of  the  word  to 
the  lymphatic  system,  will  be  met  with  only  in  extremely  rare 
cases  naturally  injected  with  decomposed  hsermatine,  in  a  condi- 
tion serviceable  for  the  microscopical  analysis.  On  the  con- 
trary, animals  fed  with  fat,  or  the  bodies  of  persons  who  have 
died  in  the  act  of  digesting  fat,  present  a  very  important  and 
instructive  natural  injection  of  the  chyle-glands.  Take  one  of 
the  smaller  mammalia, — for  example,  a  rabbit  or  a  small  dog, — 
and  introduce  a  considerable  quantity  of  milk  through  an  ceso- 
phageal  catheter  into  its  stomach.  The  animal  is  to  be  killed 
after  from  4-7  hours,  and,  as  a  rule,  the  most  exquisite  injection 
of  the  entire  chylous  system  will  be  found. 

The  recognition,  by  a  finer  analysis,  of  the  chyle-fat  in  the  in- 
terior of  a  somewhat  more  voluminous  lymphatic  gland  is,  how- 
ever, a  precarious  matter.  Fresh  sections  may  be  treated  with 
a  solution  of  albumen,  as  recommended  by  Briicke.  Attempts 
should  be  made  to  render  preparations  which  have  been  hard- 
ened in  dilute  chromic  acid  or  weak  alcohol  transparent  by 
means  of  soda  solution.  I  have  never  seen  any  great  effects 
from  drying  such  glands  either  with  or  without  a  previous  im- 
mersion in  boiling  water. 

Extremely  small  chyle-glands,  especially  those  consisting  of 
a  single  follicle,  such,  for  instance,  as  are  found  in  the  abdomi- 
nal cavity  of  the  rabbit,  when  examined  fresh  without  further 
addition,  and  in  the  condition  of  fat  assimilation,  afford,  on  the 
contrary,  handsome  appearances. 

The  self -injection  of  the  lymphatic  glands  has  also  been  em- 
ployed. Toldt  employs  for  this  purpose  a  very  finely  granula- 
ted aniline  blue,  precipitated  from  an  alcoholic  solution  by  the 
addition  of  water.  It  may  be  injected  under  the  skin  of  the 
living  animal,  and  being  conveyed  by  the  afferent  lymphatic 
vessel,  the  injection  of  the  neighboring  gland  may  be  expect- 
ed. Or,  the  lymphatic  glands  lying  in  the  vicinity  of  the  liver 
of  the  dog  may  be  selected. 

As,  according  to  Hering's  experience,  the  hepatic  lymph  of 
narcotized  creatures  is  rich  in  red  blood-corpuscles  which  have 


VESSELS    AND    GLANDS.  399 

escaped  from  the  blood-vessels,  one  may  accomplish  the  object 
by  injecting  this  aniline  mass  for  7-8  hours  in  repeated  doses 
of  12  grammes  about  every  10-15  minutes,  in  the  vena  cruralis 
of  an  animal  narcotized  with  opium. 

As  is  known,  the  human  lymphatic  glands  are  subject  to 
numerous  structural  changes.  A  part  of  the  latter  are  to  be 
regarded  as  senile  metamorphoses ;  others  are  of  a  more  patho- 
logical nature. 

Among  the  former  (which  may  also  occur  at  a  relatively 
early  period  of  life),  we  must  especially  adhere  to  three ;  name- 
ly, the  formation  of  fat-cells,  the  pigmentation  of  the  lymphatic 
glands,  and  the  metamorphosis  of  the  framework  substance 
into  ordinary  connective  tissue  with  the  gradual  destruction  of 
the  entire  organ. 

The  fat-cells  take  their  origin  from  the  connective-tissue  cor- 
puscles of  the  framework  of  the  lymphatic  gland,  and,  as  a  rule, 
affect  the  cortical  substance  of  the  gland.  It  is  only  in  rare 
cases  that  they  are  noticed  in  the  lymph-tubes  of  the  medullary 
substance.  The  glandular  structure  of  the  lymphatic  gland 
disappears  more  and  more  in  proportion  as  groups  of  fat-cells 
take  the  place  of  single  cells. 

The  pigmentation  of  the  lymphatic  glands,  as  is  known, 
affects  the  bronchial  glands  chiefly,  and  is,  after  certain  periods 
of  life,  an  almost  regular  occurrence,  although  of  extremely 
varying  degrees.  If  this  process  be  followed  from  its  very 
commencement  it  will  be  seen  that,  at  least  in  most  cases,  the 
exciting  cause  is  an  inflammatory  irritation  of  neighboring 
parts  of  the  lungs.  The  consecutive  tumefactions  of  the 
lymphatic  glands,  which  are  so  frequent  and  with  which  practi- 
cal physicians  are  familiar,  are  accompanied  by  very  extraordi- 
nary enlargements  of  their  finest  blood-vessels,  so  that,  for 
example,  almost  all  the  capillaries  are  found  to  be  dilated 
to  four  and  even  six  times  their  ordinary  diameter.  In  conse- 
quence of  these  expansions,  an  exudation  of  the  coloring  matter 
of  the  blood  takes  place  in  the  bronchial  glands  (and  under  cer- 
tain circumstances  in  the  lymphatic  glands  of  other  parts  of 
the  body  also)  so  that  the  gland,  saturated  with  a  brownish 
fluid,  assumes  a  "  splenoid "  appearance.  At  the  same  time 


400  SECTION    SIXTEENTH. 

lacerations  of  individual  vessels  and  extravasations  are  also  met 
with  here  and  there.  The  molecules  of  black  pigment  arise  by 
intermediate  stages  from  the  gradual  transformation  of  the  col- 
oring matter  of  the  blood.  These  are  seen  to  be  situated,  with- 
out conformity  to  any  law,  partly  in  the  framework  substance 
of  the  septa  and  in  the  walls  of  the  vessels.  In  many  cases  it 
is  principally  the  substance  of  the  follicles  which,  at  least  at 
the  commencement,  constitutes  the  seat  of  the  melanosis ;  in 
others  the  condition  is  reversed,  the  medulla  being  attacked. 

In  this  manner  then,  varying  extremely  in  degree,  pigmenta- 
tions of  the  bronchial  glands  take  place.  Those  of  slight  de- 
gree give  the  organ  a  sprinkled  and  spotted  black  appearance, 
but  in  higher  degrees  cause  the  black  appearance  to  extend 
over  greater  distances,  and  even  throughout  the  entire  thickness 
of  the  organ. 

While  lower  phases  of  this  melanosis  prove  to  be  relatively 
indifferent  for  the  organ  affected,  stronger  pigmentations  lead 
to  the  connective-tissue  metamorphosis  and  atrophy  of  the  lym- 
phatic gland. 

Such  connective-tissue  metamorphoses  show  bundles  of  stri- 
ated and  fibrillary  tissue,  at  first  isolated  and  then  developed  in 
the  most  extensive  manner  at  the  expense  of  the  reticular 
framework.  The  characteristic  structure  of  the  organ  disap- 
pears more  and  more,  and  finally,  together  with  the  loss  of  all 
the  lymphatic  passages,  the  whole  gland  becomes  degenerated 
into  a  connective-tissue  mass.  These  processes  are  observed 
with  pigmentations,  but  also  without  them.  The  external  lym- 
phatic glands  appear  to  be  more  subject  to  this  process  than 
those  which  are  situated  deeper  in  the  body. 

The  ordinary  methods  suffice  for  the  examination  of  the  most 
prominent  structural  conditions.  The  previous  injection  of  the 
blood-vessels  with  cold-flowing  mixtures  should,  when  possible, 
be  at  least  attempted. 

The  true  pathological  metamorphoses  of  the  lymphatic 
glands  affect  in  part  the  framework,  in  part  the  lymph-corpus- 
cles, and  in  part  both  elements  together. 

The  structural  changes  of  our  organ  in  abdominal  typhus  are 
not  very  easy  to  follow.  In  the  first,  so-called  catarrhal  period 


VESSELS    AND    GLANDS.  401 

of  this  disease,  a  tumefaction  of  the  organ  is  met  with,  which 
consists  chiefly  of  one  of  the  above-mentioned  extensive  dilata- 
tions of  the  finest  blood-vessels.  The  investing  spaces  of  the 
lymphatic-gland  follicles  are"  enlarged,  and  in  these  are  found  a 
number  of  large  multinuclear  cells  (which  may  also  be  found, 
although  in  smaller  quantity,  in  other  irritated  conditions). 
The  participation  of  the  framework-substance  appears,  on  the 
contrary,  to  be  remarkably  slight.  At  later  periods  these  cells 
break  down  under  fatty  degeneration,  and  produce  collections 
of  very  unequal  extent,  of  a  finely  granular  substance,  the  me- 
dullary typhous  matter.  Not  unfrequently  these  form  local 
softenings,  into  the  sphere  of  which  are  drawn  the  adjacent  tis- 
sues, the  framework  with  the  blood-vessels.  In  favorable  cases, 
the  finely  granular  substance  is  again  removed  by  the  efferent 
lymph-current. 

A  similar  process,  only  much  more  sluggish  in  its  pro- 
gress, is  met  with  in  tuberculous  and  scrofulous  lymphatic 
glands. 

Here,  together  with  the  breaking  down  of  the  framework 
substance,  the  same  degeneration  also  appears — a  fine,  molecu- 
lar, fatty,  waterless  matter  with  interposed,  shrunken  lymph- 
corpuscles.  These  "  cheesy  metamorphosed  "  masses  may  have 
various  destinies  allotted  to  them ;  they  may  be  reabsorbed,  be- 
come indurated  and  calcified,  or  soften  and  give  rise  to  the 
formation  of  a  fistulous  passage. 

In  other  pathological  conditions  the  participation  of  the 
framework  substance  is  more  extensive.  Thus,  in  secondary 
inflammatory  conditions  of  our  organ,  the  meshes  of  the  net- 
work are  seen  to  gradually  become  narrower,  the  trabeculse  in- 
crease in  size,  and  distinct  nuclei  are  again  formed  in  the  nodal 
points.  In  the  more  voluminous  organs,  where  the  expansions  of 
the  capillaries  already  mentioned  may  be  recognized,  there  may 
be  a  gradual  obliteration  of  the  textural  differences  of  the  septa 
of  the  medullary  and  cortical  substance.  The  lymphatic  pas- 
sages disappear,  and  the  organ  has  become  incapable  of  perform- 
ing its  functions.  The  later  appearances  of  such  lymphatic 
glands  vary  considerably,  however.  An  interesting  structural 
condition  is  sometimes  presented  in  such  cases,  by  the  enormous 
26 


402  SECTION    SIXTEENTH. 

thickenings  of  the  capillary  walls  which  are  caused  by  the 
aggregation  of  spindle-cells. 

Allied  structural  conditions  are  presented  by  the  hypertro- 
phies of  the  lymphatic  glands.  Here  the  capsule,  the  septa, 
and,  at  last,  the  medullary  substance  also,  become  transformed 
into  a  reticular  tissue,  which  i^  uniform  throughout  the  entire 
organ,  and  encloses  numerous  lymph-cells.  This  transforma- 
tion of  the  capsule  enables  one  to  appreciate  how  the  adjacent 
connective  substance  may  be  drawn  into  the  sphere  of  the  same 
metamorphosis,  and  a  fusing  together  of  the  neighboring  lym- 
phatic glands  take  place.  The  reticular  framework  is  either 
like  the  normal,  or  the  meshes  are  seen  to  be  narrower.  In 
other  cases,  the  fibres  become  much  more  strongly  developed, 
so  that  a  coarse-banded  framework,  like  that  of  a  carcinoma, 
may  be  formed.  In  the  latter  processes  the  large  nucleated 
cancer-cells  are  met  with  in  the  meshes,  varying  in  form  and 
arrangement. 

Formerly,  the  inflexible  trabecular  framework,  which  per- 
meates the  lymphatic  channels  (investing  spaces),  appeared  to 
constitute  the  chief  starting-point  of  the  metamorphosis  in  ques- 
tion, as  the  cancer-cells  arise  in  its  nodal  points,  and  its 
trabeculse  become  the  stroma  of  the  carcinoma.  At  the  present 
day,  an  original  immigration  of  the  first  cancer-cells  through 
the  vas  afferens  into  the  investing  spaces  has  become  more 
probable.  The  glandular  tissue  becomes  slowly  and  gradually 
atrophied. 

A  newer  and  more  successful  method  of  investigating  these 
diseased  lymphatic  glands  consists  in  their  injection,  and  in 
the  study  of  their  lymphatic  channels  by  the  aid  of  the  punc- 
turing method.  In  such  an  organ,  so  long  as  there  is  a  sim- 
ple tumefaction,  whereby  those  enormous  distentions  of  the 
capillary  blood-vessels  are  frequently  met  with,  the  lymphatic 
passages  are  all  permeable.  If  the  metamorphosis  of  the 
gland  progresses  further,  as  in  typhus,  and  a  breaking  down 
of  the  lymph-corpuscles  into  the  fine  granular  "  typhus  sub- 
stance "  occurs,  such  places  become  stopped  up ;  the  chan- 
nels of  hypertrophied  lymphatic  glands  likewise  become  im- 
permeable to  a  great  extent.  These  are  a  few  of  the  results 


VESSELS    AND    GLANDS.  403 

which  the  author  of  this  work  has,  thus  far,  obtained  by 
suitable  injections. 

Many  dark  points  still  exist  with  regard  to  the  origin  of  the 
lymphatic  glands  and  lymphatic  vessels  of  the  foetal  body. 
Many  years  ago  we  became  acquainted,  through  Kolliker,  with 
interesting  lymphatic  vessels  in  the  tail  of  the  frog's  larva. 
These  run  near  the  capillary  blood-vessels,  and  appear  as  deli- 
cate, twisr-like,  ramified  canals,  without  the  reticular  intercom- 

*  c5  /  ' 

manications  of  those  vessels,  and  are  characterized  by  the 
numerous  small  pouches  into  which  their  delicate  walls  are  ex- 
panded. They  contain  a  colorless  fluid,  almost  free  from  cells, 
and  it  is  certain  that  they  are  without  an  epithelial  lining. 
Aggregations  of  neighboring  spindle-cells  are  frequently  met 
with  on  the  membrane  of  the  vessel. 

We  now  turn  to  the  methods  of  investigating  glandular 
tissue. 

Three  elements  participate  in  the  formation  of  a  gland,  or 
—when  its  volume  is  greater  and  the  structure  more  compli- 
cated— of  its  subdivisions.  A  transparent,  apparently  struc- 
tureless membrane  (membrana  propria)  constitutes  the  frame- 
work, and  thus  determines  the  form  of  the  organ  or  part  of  the 
organ ;  strata  of  cellular  elements  (gland-cells)  cover  the  inner 
surface  of  the  latter  and  play  an  important  role  in  the  forma- 
tion of  secretions.  Finally,  the  external  surface  of  the  struc- 
tureless membrane  is  covered  by  a  reticulation  of  capillary 
vessels,  from  the  contents  of  which 
the  matters  for  secretion  are  taken 
in  the  form  of  watery  solutions. 

Our  fig.  200,  which  presents 
the  lower  halves  of  long,  simple, 
tubular  glands  from  the  gastric 
mucous  membrane,  may  afford 
us  a  representation  of  this  condi- 
tion. The  fine  contours  of  the 
sinuous,  blind-sack-like  tubes  pre- 
sent the  Optical  expression  Of  the  Fig.  200.  Gastric  glands  of  the  dog,  with 
.  _  cells  and  capillary  vessels. 

membrana    propria ;      nucleated 

fine  granular  cells  form  the  contents,  and  a  capillary  network, 


404  SECTION   SIXTEENTH. 

spread  out  in  the  tubular  form,  surrounds  the  individual  organ 
with  elegant  incurvations. 

None  of  the  glandular  organs  of  the  human  body  are  without 
capillaries  and  gland-cells.  This  is  not  the  case,  however,  with 
the  raembrana  propria.  It  may  be  absent,  and,  indeed,  under 
manifold  conditions.  In  the  first  place  we  see  that  the  fine 
membrane  which  is  present  in  the  earliest  period  of  life  is 
blended  with  neighboring  parts,  as  in  the  liver.  Or,  the  same 
has  been  absent  from  the  commencement,  and  a  firmly  woven, 
connective-tissue  limiting-wall  encloses  the  aggregation  of  cells 
at  all  periods  of  life.  The  latter  condition  is  shown,  in  addition 
to  other  organs  soon  to  be  mentioned,  by  the  glands  of  Lieber- 
kiihn,  a  tubular  form,  very  similar  to  the  gastric  glands  of  the 
stomach,  which  are  placed  close  together  in  the  mucous  mem- 
brane throughout  the  intestinal  canal.  Finally,  we  have  learned 
through  more  recent  researches  that  a  wicker-work  of  flattened, 
multi-radiated  connective-tissue  cells  (p.  2T4)  becomes  visible 
in  this  membrana  propria  (fig.  201).  This 
condition  has  been  especially  noticed  in 
racemose  glands  (salivary,  lachrymal,  and 
lacteal  glands'),  but  also  in  the  tubular 
glands  of  the  mucous  membrane  of  the 
stomach.  Macerating  methods  and  sec- 
tions through  hardened  preparations  are 
employed  in  these  cases.  An  entire  mus- 
ter'r°ll  °f  methods  has  been  recommended : 
vinegar;  the  33  per  cent,  solution  of  pot- 
do^SraBio57glandofthe  ash;  tlie  maceration  for  several  days  in 
iodine-serum,  and  then,  subsequently  for 
24  hours,  in  a  chromic  acid  solution  of  -fa  per  cent,  (or,  chro- 
mate  of  potash  y1-^  per  cent.) ;  the  immersion  in  osmic  acid  of 
j-  per  cent. ;  and  the  hardening  by  means  of  alcohol  or  the  bi 
chromate  of  potash,  with  subsequent  carmine  tingeing. 

However,  the  numerous  glands  of  the  human  body  are  of 
such  manifold  natures,  according  to  their  size,  their  complexity, 
and  their  entire  structure,  that  the  example  made  use  of  above 
can  in  no  wise  suffice  for  their  comprehension. 

Together  with  the  simple  tubular  glands  which  we  have 


VESSELS    AKD    GLANDS. 


405 


already  become  familiar  with  in  the  gastric  glands  of  the  stom- 
ach, other  more  complicated  ones  occur  in  which  the  lower 
caecal  extremity,  with  or  without  dividing,  forms  a  number  of 
coil-shaped  convolutions.  These  organs  have  been  provided 
with  the  appropriate  name  of  convoluted  glands.  The  most 
extended  and  familiar  example  of  them  is  presented  by  the 
sudoriparous  glands  of  the  skin  (fig.  202,  a,  fy.  The  network 


Fig.  202.  A  human  sudoriparous  gland,  a,  the  coil,  surrounded  by  the  commencement  of 
venous  vessels;  ft,  the  excretory  duct;  c,  the  basket-like  capillary  plexus  surrounding  the  coil,  and 
the  arterial  trunk. 


of  vessels  which  encircles  the  coil  becomes  a  sort  of  wicker-work 
with  rounded  meshes  (c).  The  kidney  and  the  testicle,  two 
large,  voluminous  organs  of  the  body,  present  much  longer 
cylindrical  tubes  with  divisions  and  reticular  intercommuni- 
cations. Fig.  203  represents  these  glandular  tubes  of  the  kid- 
ney, the  so-called  uriniferous  tubes  (1,  2). 

Another  form  of  glands,  the  racemose,  is  very  widely  diffused. 

Roundish  sacks  (gland- vesicles),  which  are  smaller  or  larger, 
longer  or  shorter,  have  their  outlets  associated  together  in 
groups.  Such  groups  of  sacks  (gland-lobules)  are  again  united 
by  short  ducts  and  by  elongations  of  the  membrana  propria, 
and  thus,  sometimes  in  a  slightly,  sometimes  more  considerably 
(fig.  204),  and  sometimes  extremely  complicated  manner,  the 


406 


SECTION    SIXTEENTH. 


racemose  gland  is  formed.  The  changes  which  are  here  to  be 
observed,  and  the  manner  in  which  the  efferent  canal- work 
gradually  advances  to  a  more  compound  texture — these,  as  well 
as  many  other  particulars,  must  be  learned  by  reference  to  the 
text-books  on  histology. 


Fig.  203.  TJriniferous  tubes  from 
the  human  kidney.  1.  Side  view; 
a  &,  canals  filled  with  cells ;  c,  one 
partially  free  from  cells ;  2,  trans- 
verse section  of  the  same  ;  3,  gland- 
cells. 


Fig.  204.  Human  Brunner's  glands. 


Notwithstanding  many  subordinate  variations,  there  is  one 
and  the  same  fundamental  design  present  in  all,  and  easy  to  be 
observed  from  the  mucous  follicles,  which  are  to  be  called 
almost  microscopical,  to  the  most  voluminous  examples,  such  as 
the  salivary  glands  and  the  pancreas. 

The  gland-cells  (which  we  have  still  to  mention  more  espe- 
cially) present  numerous  variations  according  to  the  nature  of 
the  actual  secretion  ;  the  capillary  network  surrounding  them, 
on  the  contrary,  always  exhibits  circular  meshes  (fig.  205). 

There  is  still  a  third  form  of  glandular  organs  ;  such,  namely, 
in  which  the  membrana  propria  constitutes  a  roundish  vesicle, 
closed  on  all  sides,  with  cells  in  its  interior,  and  surrounded 
externally  with  a  network  of  capillaries  ;  the  entire  organ  being 
composed  of  a  large  or  larger  proportion  of  such  vesicles  em- 
bedded in  a  connective-tissue  groundwork. 

The  ovary  (fig.  206)  represents  the  latter  arrangement.     Its 


VESSELS   AND    GLANDS. 


407 


Fig.  205.  Vascular  network  of  the  rabbit's  pancreas. 

gland- vesicles,  called  Graafian  follicles  (0,  d),  contain,  together 
with  small  roundish  gland-cells,  a  large  globular  cell,  the  ovum. 
The  latter,  by  the  rupture  of  the  (rather  complicated)  wall, 


Fig:.  206.    Ovary  of  the  rabbit,   a,  epithelium  (serosa) ;  6,  cortical  or  external  fibrous  layer ;  c, 
youngest  follicle ;  d,  a  somewhat  more  developed  older  one. 


408  SECTION    SIXTEENTH. 

ing  arrived  at  the  end  of  its  existence,  undergoes  a  process  of 
cicatrization  as  the  corpus  luteum,  as  it  is  called. 

Still  another  variety  of  such  glands  with  closed  vesicles  has 
been  assumed.  The  capsules  are  said  to  form  a  secretion  in 
their  interior  from  the  elements  of  the  blood,  and  when  the 
secretion  is  perfected,  it  is  consigned  to  the  blood  and  lymphatic 
vessels  for  removal.  This  is  a  very  unsatisfactory  explanation 
of  the  dilemma,  arising  from  the  experience  that  such  a  dehis- 
cence  as  is  exhibited  by  the  ovary  is  never  observed  in  the 
organs  in  question. 


Pig.  207.     Thyroid  gland  of  the  child,    a,  connective-tissue  framework ;  6,  capsules ;  c,  their 
gland-cells. 

They  were  formerly  rather  liberal  in  the  acceptation  of  such 
organs,  so-called  "  blood  vascular  glands."  At  present  we  have 
learned  to  separate  many  of  them  as  belonging  to  the  lymphatic 
glands,  or,  at  least,  as  being  nearly  related  to  them  ;  such  as  the 
thymus,  the  spleen,  the  Peyerian  and  solitary  follicles  of  the 
intestines,  the  tonsils,  and  the  conjunct! val  follicles.  Only  a 
limited  number  of  enigmatical  structures,  especially  the  thyroid 
gland  (fig.  207),  the  supra-renal  capsules,  and  the  hypophysis 
cerebri  still  find  a  place  here. 

The  alleged  membrana  propria  (fig.  207  I)  which  former 
observers  believed  that  they  saw  on  these  structures,  appears  in 
reality,  however,  not  to  exist.  We  believe  that  its  presence,  at 


VESSELS   AND    GLANDS. 


409 


least  in  the  hypophysis  cerebri,  the  supra-renal  capsules,  and 
the  thyroid  gland  must  be  denied.  The  predecessors  were 
deceived,  in  consequence  of  inefficient  methods  of  examination, 
by  the  compactly  arranged  connective-tissue  parietes. 

Finally,  the  cellular  constituents  of  our  organ  are  of  greater 
importance.  The  gland-cells  proceed,  as  we  have  learned  in 
the  most  certain  manner  from  Remak's  admirable  investigations, 
from  the  foetal  epithelial  layers,  the  so-called  horn  and  intestino- 
glandular  lamellae,  and  present  originally  partly  solid  cell- 
growths,  partly  hollow  diverticula.  In  accordance  with  this, 
much  of  their  character  remains  closely  allied,  in  all  their  pro- 
cesses of  life,  to  the  nature  of  epithelium,  and,  even  in  the 
excretory  ducts  of  the  glands,  the  continual  transition  into  the 
adjacent  epithelial  tissues  may  be  observed. 


Fig.  2158.  Human  liver- 
cells,  with  a  single  nucle- 
us at  a ;  one  with  two 
nuclei  at  6. 


Fig.  209.  So-called  mucous  gastric 
glands.  1.  From  the  cardiac  portion 
of  the  hog's  stomach ;  a,  the  cylin- 
drical cells  (at  1*  isolated) ;  6,  the 
lumen.  2.  From  the  pylorus  of  the 
dog. 


The  cells  which  we  meet  with  in  the  various  glands  are  in 
part  circular,  in  part  flattened,  and  in  part  cylindrical  nucleated 
cells  (fig.  208  and  209).  As  a  rule,  especially  with  a  certain 


410  SECTION   SIXTEENTH. 

amplitude  of  the  passages,  these  cells  clothe  the  inner  wall 
after  the  manner  of  epithelium  (fig.  209),  so  that  a  lumen  still 
remains,  and  only  narrow  passages,  such,  for  instance,  as  those 
of  the  liver,  are  found  to  be  filled  up  by  several  cells  placed  one 
behind  the  other.  In  consequence  of  mismanagement  in  the 
preparation,  as  well  as  of  cadaverous  decomposition,  these 
aggregated  gland-cells  generally  become  detached  and  fre- 
quently fill  the  entire  cavity  of  the  gland  with  fragmentary 
structures,  and  even  free  nuclei  and  molecules. 

The  gland-cells  display  their  relationship  to  the  epithelial 
structures,  at  least  partially,  in  still  another,  and  indeed  physi- 
ological manner ;  namely,  by  a  certain  transitoriness  of  their 
existence,  and  by  their  falling  off  from  the  glandular  walls. 
Although  the  duration  of  their  life  varies  to  a  greater  extent, 
and  though  many  gland-cells,  such  as  those  of  the  liver  and  of 
the  renal  passages,  are  of  a  more  persistent  nature,  so  that  the 
formation  and  excretion  of  certain  secretory  elements  is  repeat- 
ed by  them  for  a  longer  time,  there  are  also,  on  the  other  hand, 
many  examples  of  a  more  rapid  separation.  At  every  act  of 
gastric  digestion  numerous  cells  of  the  gastric  glands  become 
separated  from  their  parent  tissues  and  cover  the  inner  surface 
of  the  stomach,  at  least  in  certain  mammalia,  with  a  thick 
mucous  covering.  Other  glands  which  prepare  a  fatty  secre- 
tion present,  as  a  physiological  process,  the  fatty  degeneration 
of  the  cells,  and  in  this  way  innumerable  quantities  of  the  latter 
are  destroyed.  In  this  manner,  by  the  destruction  of  innumer- 
able cells,  is  formed  the  secretion  of  the  sebaceous  follicles, 
many  sudoriparous  and  Meibomian  glands,  and  likewise  of  the 
lacteal  glands. 

An  example  of  this  physiological  cell  destruction  may  be 
represented  by  fig.  210,  the  ovoid  vesicle  of  a  sebaceous  gland. 

This  appears  at  a  to  be  lined  by  stratified  layers  of  rounded 
cells  in  which  the  fat-molecules  are  to  be  recognized,  sometimes 
in  smaller,  sometimes  in  larger  quantities.  Other  cells  (&),  con- 
taining a  larger  quantity  of  fat,  are  already  separated  from  the 
parental  tissues,  and,  already  in  part  undergoing  dissolution,  fill 
the  cavity  of  the  gland  vesicle.  In  this  way  is  explained  the 
occurrence  of  free  masses  of  fat  in  the  lower  educting  portion 


VESSELS    AND    GLANDS.  411 

of  the  latter ;  in  this  way,  also,  is  formed  the  smegma  cnta- 
neum.  The  various  cells  of  this  form  of  gland  are  seen  at  J?, 
a-f,  more  highly  magnified. 


Fig.  210.     Human  sebaceous  follicle.     A,  gland- vesicle  with  the  cells  resting  on  the  wall  at  a, 
and  separated  and  overloaded  with  fat  at  6 ;  B,  a-/,  several  of  these  gland-cells. 

In  examining  the  gland-cells  (the  investigation  of  which 
in  the  living  condition  has,  nnfortnnately,  been  almost  entirely 
neglected),  the  most  conservative  treatment  is  necessary.  Sec- 
tions made  through  an  entirely  fresh  part  yield  to  a  knife- 
blade  which  is  moved  or  scraped  over  it,  masses  which,  spread 
out  in  an  indifferent  fluid,  will  often  afford  satisfactory  ex- 
amples of  the  cells  in  question.  Glands  will  occasionally 
be  met  with,  which,  in  a  condition  of  vital  warmth,  are  so  solid 
that  with  a  very  sharp  and  moistened  razor  very  thin  sections 
may  be  made  from  them.  When  these  sections  are  examined 
in  indifferent  media,  such  as  iodine-serum  or  extremely  dilute 
chromic  acid,  they  show  the  position  of  these  cells,  and  also 
permit  of  their  isolation  by  proper  picking.  Generally,  how- 
ever, sur.h  procedures  fail  in  consequence  of  the  softness  of  the 
structure.  We  therefore  recommend  the  freezing  method 
as  the  best  procedure  at  present  in  use  for  this  purpose. 
Hardening  methods  have  been  used  for  a  long  time  for  the 
examination  of  cells  in  situ.  Drying  the  organ  is  not  to  be 
recommended,  as  deeper  alterations  of  the  cells  and  the  subse- 
quent separation  of  many  of  these  structures  can  scarcely 
be  avoided.  It  is  better  to  employ  a  solution  of  chromic  acid 
or  of  the  bichromate  of  potash  of  gradually  increasing  strength, 
by  means  of  which  excellent  preparations  may  be  obtained. 


412  SECTION"    SIXTEENTH. 

The  immersion  of  small  pieces  of  the  glands,  removed  from  the 
body  immediately  after  death,  in  a  large  quantity  of  absolute 
alcohol,  is  an  excellent  procedure,  and  the  proper  consistence  is 
obtained  in  a  few  hours. 

Tingeing  the  gland-cells  may  be  best  accomplished  with 
glycerine-carmine,  Ranvier's  mixture  of  picric  acid  and  car- 
mine, or  a  solution  of  hsematoxyline. 

It  is  scarcely  necessary  to  mention  that  the  application  of 
numerous  chemical  reagents  is  necessary  for  the  recognition  of 
the  contents  of  these  cells,  as  well  as  that  the  freshest  possible 
tissue  is  to  be  used  for  this  purpose. 

Solutions  of  the  alkalies,  ammonia,  potash,  and  soda,  are  most 
to  be  recommended  for  the  demonstration  of  the  membrana 
propria  of  the  glands. 

There  are  various  methods  for  us  to  select  from  for  the  inves- 
tigation of  the  relations  of  the  last-named  membrane,  as  well  as 
of  the  entire  structure  of  the  glands.  Drying,  with  the  subse- 
quent action  of  alkalies  on  the  moistened  sections,  is  to  be 
employed  with  advantage  for  many  parts,  as,  for  example,  for 
the  glands  of  the  skin  and  eyelids.  If  one  desires  to  study  the 
organs  which  are  embedded  in  mucous  membranes,  boiling  the 
piece  in  question  in  vinegar  and  then  drying  it  is  to  be  recom- 
mended. It  is  also  well  to  use  this  preparatory  treatment  with 
vinegar  for  the  skin,  the  lacteal  glands,  and  likewise  for  the 
kidneys. 

In  the  moist  condition  we  can  often  obtain  a  sufficient  hard- 
ening by  means  of  pyroligneous  acid,  and,  as  in  the  previously 
mentioned  process,  in  consequence  of  the  connective  tissue 
being  rendered  transparent,  we  obtain  good  views  from  thin 
sections. 

The  three  above-mentioned,  so  frequently  employed  fluids — 
alcohol,  solutions  of  chromic  acid,  and  of  the  bichromate  of  pot- 
ash— appear,  however,  to  be  more  important,  and,  in  fact,  they 
generally  suffice  for  the  glandular  tissues.  Where  brushing  is 
unnecessary,  the  tissues  may  be  energetically  hardened  with 
stronger  degrees  of  concentration.  But  if  one  desires  to  make 
use  of  the  procedure  just  mentioned — and  it  is  of  the  greatest 
value  for  the  recognition  of  the  framework  of  the  glands,  the 


VESSELS   AND    GLANDS.  413 

vessels,  incidental  muscles,  etc. — the  matter  should  not  be  over- 
done. Notwithstanding  every  precaution,  however,  many  vari- 
ations will  still  be  met  with.  Sections  of  the  kidney  and  of  the 
testicle,  and  surface  sections  of  the  gastric  mucous  membrane 
are  generally  easy  to  brush ;  it  is  difficult,  on  the  contrary,  to 
obtain  good  preparations  from  the  liver.  The  chloride  of  pal- 
ladium is  to  be  used  for  recognizing  the  muscular  elements  in 
glands. 

The  fine  blood-vessels  which  encircle  the  glands  are  gener- 
ally concealed  by  the  cellular  contents  of  the  glands,  and  even 
after  the  most  careful  brushing  are  only  very  imperfectly 
brought  to  view.  The  artificial  injection  with  transparent 
masses,  a  light  blue,  should  not  therefore  be  omitted.  This 
procedure  naturally  varies  considerably  according  to  the  indi- 
vidual organs. 

Injections  are  employed  in  still  another  way  for  glands, 
naturally  only  the  more  voluminous  ones ;  namely,  for  filling 
their  cavities.  Cold-flowing  masses  (either,  and  preferably, 
purely  watery  ones,  or  at  most  mixed  with  glycerine,  but  not 
alcohol),  entirely  fresh  organs,  and  great  care  are  necessary  if 
such  experiments  are  to  be  successful.  The  employment  of  a 
constant  pressure  is  decidedly  preferable  to  the  syringe  for  this 
purpose. 

By  these  means,  a  plexus  of  very  fine  canals,  the  "gland-capilla- 
ries," surrounded  by  an  extremely  delicate  sheath,  has  frequently 
been  recognized  in  an  interesting  manner,  lying  between  the 
secreting  cells  and  surrounding  each  one  of  them.  The  presence 
of  this  network  in  the  liver  has  been  known  for  some  time. 
We  shall  have  to  mention  these  biliary  capillaries  hereafter. 
Within  a  few  years  they  have  also  been  discovered  in  racemose 
glands,  as  in  the  pancreas  (Langerhans,  Saviotti,  Gianuzzi),  in 
the  salivary  glands  (Pniiger  and  Ewald),  in  the  lachrymal 
gland  (Ball),  and  in  the  lacteal  gland  (Gianuzzi  and  Falaschi). 
Our  fig.  211  may  represent  these  remarkable  canals,  which 
here  run  partly  between  the  cells  themselves,  partly  on  the 
surface  between  them  and  the  membrana  propria. 

For  the  investigation  of  foetal  glands,  embryos  hardened  in 
absolute  alcohol  or  chromic  acid  are  to  be  chosen,  and  sections 


414 


SECTION    SIXTEENTH. 


made  through  them  in  various  directions.  The  separated  skin, 
as  well  as  mucous  membranes,  often  present  very  good  surface 
views.  The  origin  of  the  membrana  propria,  whether  it  takes 
place  from  the  cell-aggregation  by  a  process  of  separation,  or 


Fig.  211.  Glandular  canals  from  the  pancreas  of  the  rabbit,  injected  with  Briicke's  Prussian 
blue ;  after  Saviotti.  1  and  2 ;  a,  larger  excretory  duct ;  6,  that  of  an  acinus  ;  c,  finest  capillary 
duct.  3,  an  acinus  with  cells  and  only  partially  filled  gland-capillaries. 


is  formed  from  the  neighboring  tissues  in  consequence  of  an 
aggregation  of  the  same,  requires  more  accurate  investigation 
than  has  thus  far  been  devoted  to  it. 

We  would  add  a  few  words  in  closing,  touching  the  patho- 
logical conditions  of  the  glandular  tissues. 

The  gland-cells  (corresponding  to  their  epithelial  nature) 
present  the  phenomena  of  hypertrophy  and  degeneration,  but 
scarcely  that  of  a  transformation  into  other  tissues.  This  takes 
place,  as  a  rule,  more  from  the  connective-tissue  framework 
substance  which  permeates  the  organ,  to  which,  perhaps,  the 


VESSELS    A]ST>    GLANDS. 


415 


so-called  membrana  propria  of  the  gland  is  to  be  reckoned 
throughout. 

Hypertrophies  of  a  gland  show,  as  a  rule,  an  increase  in 
number  of  the  secreting  cells,  which  we  at  present  ascribe  to 
a  more  active  process  of  division ;  although  the  existing  cells 
may  also  increase  in  size,  and  thus  cause  an  increase  of  volume. 
Both  conditions  are  found,  for  example  (frequently  enough  com- 
bined), in  hypertrophied  livers. 

We  have  already  mentioned  above  the  accumulation  of  fat 
in  the  interior  of  the  cells  we  are  at  present  considering.  For 
many  glandular  organs  it  constitutes  an  entirely  normal  occur- 
rence. In  others  such  a  destruction  of  the  cells  is  an  abnormal 
phenomenon,  a  process  of  degeneration.  Pigmentations  of 
the  gland-cells  are  more  rare;  amyloid  degenerations  occur 
in  these  structures,  at  least  in  many  cases,  while,  as  a  rule, 
they  affect  the  vessels  and  the  connective-tissue  portions  of  the 
gland. 

Colloid  degenerations  occur  in  certain 
glands  at  least,  and  affect  their  cells 
quite  extensively,  especially  in  the  thy- 
roid (fig.  212). 

Swelling  of  the  connective  tissue,  in- 
crease of  the  interstitial  substance,  dis- 
tention  of  the  connective-tissue  corpus- 
cles and  the  division  of  their  nuclei,  are 
met  with  in  conditions  of  simple  inflam- 
matory irritation.  A  more  persistent 
increase  of  the  connective-tissue  of  the 
gland  may  lead  to  the  destruction  of  the 
gland-cells  in  the  compressed  cavities. 
That  tuberculous  and  typhous  degener- 
ations, and  carcinomatous  new  forma- 
tions in  glandular  organs,  also  take  their 

origin  from  the  connective  tissue,  has  hitherto  been  the  general 
modern  acceptation.  Our  present  knowledge  concerning  the 
structural  changes  of  the  liver  and  kidneys  may  constitute  an 
important  starting-point  for  subsequent  investigations  of  smaller 
glandular  organs. 


Fig.  212.  Colloid  degenera- 
tion of  the  gland- vesicles  of  the 
thyroid,  a,  from  the  rabbit ;  &, 
from  the  calf,  at  the  beginning. 


416  SECTION   SIXTEENTH. 

Cysts,  according  to  experience,  frequently  originate  from 
glandular  passages  when  the  secretion,  in  consequence  of  ob- 
struction to  its  egress,  accumulates  more  and  more  and  distends 
the  duct. 

The  new  formation  of  glandular  tissue  and  of  entire  glandu- 
lar organs  is  likewise  not  an  unf requent  occurrence.  The  former 
is  seen  in  hypertrophied  structures.  Entire  glands  occur  in 
mucous  polypi.  We  also  meet  with  tubular  and  sebaceous 
glands,  together  with  hairs,  teeth,  etc.,  in  cysts  of  the  ovary. 

There  are  no  special  methods  of  investigation  to  be  men- 
tioned here. 


Section  0CDcntecntl) 

DIGESTIVE   ORGANS. 

THE  study  of  the  digestive  apparatus,  its  parietes,  the  glands 
connected  with  it,  and  the  substances  which  it  contains,  consti- 
tutes an  extensive  section  of  microscopic  investigation.  In  con- 
sequence of  the  decomposition  which  so  readily  takes  place  in 
them,  most  human  bodies  appear  but  little  adapted  for  this 
purpose,  so  that  for  many  textural  conditions,  recourse  is  more 
advantageously  had  to  a  recently  killed  mammalial  animal. 
The  bodies  of  new-born  children  are  still  better  adapted. 

The  lips  present  a  transition  of  the  tissue  of  the  external  in- 
tegument to  that  of  the  mucous  membrane,  as  well  in  its 
epithelial  as  in  its  fibrous  layers.  The  finer  structure  of  the 
same  is  to  be  examined  either  in  dried  preparations  (also  pre- 
viously boiled  in  vinegar),  or  those  which  have  been  hardened 
by  means  of  alcohol  or  chromic  acid.  The  small  sebaceous 
follicles,  which  were  discovered  in  them  a  few  years  ago,  may  be 
recognized  without  much  difficulty  by  the  application  of  acetic 
acid. 

In  the  oral  and  pharyngeal  cavities  are  presented  for  exam- 
ination the  mucous  membrane  with  the  small  glands  belong- 
ing to  it,  the  teeth  (already  described),  the  tongue,  the  tonsils 
and  lingual  follicles,  and  finally  the  salivary  glands  as  well  as 
the  secretion  of  the  oral  cavity,  the  saliva. 

In  order  to  accomplish  the  injection,  which  is  so  necessary,  of 
this  commencing  portion  of  the  digestive  tract,  we  would  rec- 
ommend the  use  of  the  smaller  mammalial  animals  and  the 
insertion  of  the  canule  in  the  arch  of  the  aorta,  as  mentioned 
above  (p.  356),  for  the  brain.  A  complete  injection  of  the  oral 

cavitv,  the  tongue,  and  the  pharynx  may  be  readily  obtained  in 

27 


418 


SECTION    SEVENTEENTH. 


this  way.     A  blue  deserves  the  preference  on  account  of  the 
subsequent  carmine  tingeing. 

The  mucous  membrane,  with  its  papillae,  vessels,  nerves,  and 
glands,  may  be  reviewed  in  vertical  sections  of  fresh  prepara- 
tions made  as  thin  as  possible,  and  then  rendered  still  more 
transparent  by  means  of  solutions  of  soda,  or  dilute  acetic  acid. 
It  is  always  a  tedious  affair,  however,  to  obtain  these  from  such 
a  soft  and  slippery  tissue,  so  that  naturally  the  customary  hard- 
ening methods  are  also  extensively  employed. 

The  mucous  membrane  and 
numerous  conical  or  filamen- 
tous papillae,  covered  by  the 
thickly  stratified  pavement 
epithelium,  may  be  recognized 
with  facility  in  good  alcoholic 
preparations  (fig.  213).  The 
numerous  racemose  or  mu- 
cous glands  of  the  oral  cavity 
are  rendered  apparent  by  the 
application  of  this  acid  or, 
still  better,  after  the  use  of 
alkaline  solutions.  Their  ve- 
sicles frequently  appear  con- 
siderably elongated  (Puky, 
Akos),  and  their  gland-cells 

cylindrical.     The   gingival   mucous   membrane    of   the  rabbit 
constitutes  a  beautiful  object  for  this  purpose. 

In  order  to  recognize  the  general  arrangement  of  the  nerves, 
the  gradual  hardening  with  weak  solutions  of  chromic  acid  or 
chromate  of  potash,  with  the  subsequent  employment  of  a  very 
dilute  acetic  acid,  is  to  be  recommended.  An  immersion  of  the 
fresh  tissue  in  the  acetic-acid  water  (1-2  drops  of  acetic-acid 
hydrate  to  50  ccm.),  mentioned  at  the  examination  of  the  mus- 
cular nerves,  affords,  after  12-24  hours,  very  suitable  specimens, 
especially  with  the  lower  vertebrate  animals.  Pyroligneous 
acid  has  been  frequently  employed  here.  Osraic  acid  and 
chloride  of  gold  are  to  be  tried  for  more  accurate  studies. 
The  examination  of  the  tongue  requires  various  methods,  ac- 


Fig.  213.    Injected  papilla  from  the  gum  of 
a  child. 


DIGESTIVE    ORGANS.  419 

cording  to  the  portion  of  the  structure  of  the  complicated  organ 
which  one  desires  to  investigate. 

To  follow  the  general  arrangement  of  the  muscles,  one  may 
use  tongues  which  have  been  for  a  long  time  in  alcohol,  also 
fresh  ones,  which  must  be  boiled  in  water,  however,  until  they 
have  become  quite  soft.  To  obtain  finer  sections,  hardening  in 
alcohol  or  the  freezing  method  may  be  employed.  Thin  sec- 
tions afford  beautiful  specimens  after  being  tinged  with  car- 
mine and  washed  in  acetic-acid  water,  or  stained  with  hsema- 
toxyline,  or  with  carmine  and  picric  acid,  after  Schwarz's 
method,  and  likewise  by  the  direct  application  of  acetic  acid  or 
dilute  solutions  of  soda.  The  tongues  of  the  smaller  mammalia 
deserve  the  preference  to  those  of  larger  animals,  and  likewise 
those  of  embryos  to  those  of  older  creatures. 

Considerable  attention  has  been  paid  for  some  time  to  the 
divisions  of  the  filaments  of  the  lingual  muscles.  They  may  be 
readily  discovered  in  the  lower  amphibia,  frogs,  tritons,  etc.,  by 
means  of  the  usual  maceration  in  dilute  pyro-acetio  acid ;  an 
immersion  in  a  very  dilute  solution  of  chromic  acid  is  also  to  be 
recommended.  The  strong  muriatic  acid  (see  p.  129)  has  been 
subsequently  employed  for  this  purpose,  and  the  divided  fila- 
ments have  also  been  perceived  in  the  human  tongue  (Ripp- 
mann).  The  connection  of  the  muscular  fibres  which  ascend 
into  the  papillae  of  the  frog's  tongue  with  the  connective-tissue 
corpuscles,  which  was  observed  by  Billroth  and  corroborated  by 
Key,  is  to  be  followed  in  pyro-acetic  acid  preparations. 

The  mucous  membrane  of  the  human  tongue,  with  its  pave- 
ment epithelium,  does  not  require  any  special  methods.  The 
epithelial  processes  of  the  papillae  filiformes  are  often  quite  long, 
and  their  formation  out  of  individual  cells  may  be  recognized 
after  the  application  of  alkalies. 

The  nerve-terminations  of  the  tongue  will  be  mentioned  fur- 
ther below  at  the  organs  of  sense. 

In  larger  animals,  also,' the  injection  of  the  blood-vessels  does 
not  present  any  difficulties.  The  familiar  puncturing  method 
serves  for  the  lymphatics  and  the  lymph-passages  in  general, 
which  are  quite  abundant  in  the  tongue,  and  form  cul-de-sac- 
like  axile  canals  in  the  papillae  filiformes. 


420  SECTION    SEVENTEENTH. 

Glycerine  is  adapted  for  mounting  permanent  preparations, 
or,  after  tingeing,  Canada  balsam.  Excellent  preparations  are 
obtained  by  the  latter  method,  which  permit  of  the  recognition 
of  many  histological  details,  not  only  of  the  commencement, 
but  also  of  the  entire  digestive  tract. 

Of  late  years  the  tongues  of  mammalial  animals  have  also 
become  important  and  profitable  objects  for  experimental  pa- 
thologists.  On  them  Wywodzoff  and  Thiersch  have  studied  the 
healing  process  of  wounds.  The  injection  of  the  blood-vessels 
with  gelatine  cannot  be  dispensed  with  in  these  cases.  To  ren- 
der the  tissue  of  the  organ  injected  with  carmine  visible,  Thiersch 
made  use  of  a  modified  silver  impregnation.  He  dissolved  1 
part  of  nitrate  of  silver  in  5,000  parts  of  alcohol,  and  placed  the 
sections  in  it  for  5  minutes,  with  repeated  shaking.  They  are 
then  to  be  shaken  for  a  few  seconds  in  a  saturated  alcoholic  solu 
tion  of  chloride  of  sodium,  after  which  they  are  to  be  exposed 
to  the  light.  They  now  show  their  histological  details  beau- 
tifully, and  may  be  mounted  permanently  in  a  resinous  sub- 
stance. 

"We  may  rapidly  pass  over  the  methods  of  examining  the  ton- 
sils (fig.  214)  and  the  lingual  follicles,  for  they  are  the  same  as 


Fig.  214.  Tonsil  of  the  adult  (after  Schmidt),  or,  larger  excretory  duct ;  &,  more  simple  one  ;  c, 
lymphoid  parietal  layer,  with  follicles ;  d,  lobule,  reminding  one  of  a  lingual  follicle ;  e,  superficial, 
f,  deeper  mucous  follicle. 

for  other  lymphoid  organs.  Here  also  chromic  acid,  bichro- 
mate of  potash,  and  alcohol  are  employed  as  hardening  media. 
Thin  sections,  cautiously  brushed  and  tinged,  readily  permit 
of  the  recognition  of  the  structure.  In  consequence  of  the 
numerous  diseases  of  the  tonsils,  however,  the  precaution  should 
be  observed  to  use  the  bodies  of  new-born  or  small  children ; 


DIGESTIVE    OKGANS.  421 

likewise  the  younger  specimens  among  mammalial  animals. 
Of  these,  I  would  especially  recommend  dogs,  pigs,  and  calves. 
The  puncturing  method,  cautiously  performed  beneath  the  in- 
vesting tissues,  fills  the  numerous  lymphatics  in  the  calf  and  ox 
without  difficulty ;  with  somewhat  more  trouble  in  the  dog ;  but, 
according  to  previous  experience,  extremely  seldom  in  a  satis- 
factory manner  in  the  hog. 

The  glandular  follicles  of  the  tongue  are  difficult  to  inject; 
the  recognition  of  their  structure  is,  on  the  contrary,  relatively 
easy. 

To  obtain  the  salivary  corpuscles  which  exude  from  the  cavi- 
ties of  the  tonsils,  pressure  should  be  cautiously  made  on  a 
tonsil  immediately  removed  from  a  calf  which  has  just  been 
killed.  A  thick,  glairy  mucus,  containing  a  number  of  these 
cells,  will  then  make  its  appearance. 

The  salivary  glands  have  been  frequently  examined  of  late. 
A  whole  series  of  methods  of  investigation  has  been  given. 
Heideiihain  and  Pfliiger  employ  absolute  alcohol  for  hardening, 
and  a  subsequent  conservative  tingeing  with  carmine.  Picked 
preparations  may  be  made  from  fine  sections  of  the  entirely 
fresh  organ,  by  adding  the  gland  secretion,  humor  aqueus,  iodine- 
serum,  or  a  very  dilute  chrornic-acid  solution  (0.02-0.04  per 
cent.),  with  a  slight  addition  of  the  previously  mentioned  fluid. 

Heidenhain  recommends  for  maceration  iodine-serum,  chro- 
mic acid  (^V~  J  gr-  *°  ^ne  oz-)?  or  bichromate  of  potash  (J-15  gr.). 
Acidulated  water  (0.02  per  cent,  glacial  acetic  acid),  with  the 
subsequent  immersion  in  chromic  acid  (y1^  gr.  to  the  ounce),  also 
affords  good  preparations. 

Pfliiger  employs  the  action  of  iodine-serum  for  from  4-6 
days,  either  alone  or  with  the  subsequent  immersion  in  chromic 
acid  of  0.02  per  cent.  It  is  furthermore  very  good  to  place  the 
organ  (the  submaxillary  gland  of  the  rabbit)  in  a  small  glass  ves- 
sel, and  to  add  4  to  8  drops  of  the  chromic-acid  solution,  and, 
after  an  hour,  when  the  gland  has  become  hardened  by  swelling, 
to  make  fine  sections  from  it  for  the  purpose  of  picking.  The 
33  per  cent,  solution  of  potash  also  deserves  to  be  employed. 
Osmlc  acid  serves  for  the  nerve  termination. 

Krause  employed  molybdenate  of  ammonia,  with  the  sub- 


422  SECTION    SEVENTEENTH. 

sequent  use  of  tannic  or  pyrogallic  acid  (p.  158).  Finally, 
Ranvier  used  for  macerating,  dilute — for  hardening,  concentrated 
picric  acid,  and  for  the  latter  preparations  tingeing  with  picro- 
carmine  (p.  160).  The  injection  of  the  blood-vessels  of  the  sub- 
maxillaiy  gland  of  the  dog,  for  instance,  is  not  difficult.  For 
the  recognition  of  the  lymph-passages  Gianuzzi  recommends 
exciting  a  condition  of  oedema  in  the  same  organ.  The  natural 
injection  may  be  employed  here,  the  gland  being  ligated  at 
the  hilus,  and  removed  with  the  preservation  of  the  capsule,  and 
hardened  for  a  few  days  in  a  solution  of  chromate  of  potash, 
and  then  placed  in  alcohol.  Or  the  gland  may  be  removed,  and 
then  carefully  injected  by  the  artery  with  colored  gelatine,  the 
aperture  of  the  vein  being  left  open.  It  is  then  to  be  hung  in 
alcohol  for  a  few  days,  in  order  that  the  capsule  may  be  render- 
ed more  firm  ;  and,  finally,  a  puncture  is  to  be  made  near  the 


Fig.  215.  The  submaxillary  gland  of  the  dog.  a,  mucous  cells ;  6,  protoplasma  cells ;  c,  Gia- 
nuzzi's  crescent ;  d,  transverse  section  of  an  excretory  duct,  with  the  peculiar  cylindrical  epithe- 
lium. 

artery,  at  the  place  where  it  sinks  into  the  gland-tissue  at  the 
hilus. 

The  submaxillary  glands  of  many  of  the  mammalial  animals, 
such  as  those  of  the  dog  and  the  cat  (but  not  those  of  the  rab- 
bit), are  mucous  glands.  In  the  quiescent  organ  (fig.  215)  one  may 
recognize,  together  with  granular  cells  containing  protoplasma 


DIGESTIVE    ORGANS.  423 

(&),  which  frequently  present  a  small  and  compressed  semilunar 
structure  (c)  at  the  border  of  the  gland-vesicle  (the  "  crescent " 
of  Gianuzzi),  other  gland-cells  (a)  which  are  larger  and  of  a 
hyaline  transparency,  whose  contents  are  not  reddened  by  car- 
mine, and  which  prove  to  be  mucous.  Our  figure  shows  still 
another  peculiar  condition  which  is  very  easy  to  recognize,  a 
delicate  longitudinal  striation  of  the  cylindrical  epithelial  cells 
in  the  excretory  duct  (d). 

When  Heidenhain  had  induced  an  increased  secretion  in  the 
submaxillary  gland  of  the  dog  by  a  prolonged  irritation  of  the 
nerves,  an  entirely  different  appearance  presented  itself  (fig. 
216).  The  mucous  cells  had  nearly  all  disappeared,  and  in  their 
place  the  acinus  was  filled  by  granular  structures  alone,  which 
were  rich  in  protoplasma  (a). 

If  it  be  desired  to  attempt  the  injection  of  the  canal  system 
(p.  413),  cold-flowing  blue,  without  alcohol,  is  the  best  injection 
fluid. 

Finally,  the  condition  of  the  oral  cavity  and  the  fluids  which 
it  contains  also  require  a  short  notice.  The  latter  consist  of  the 
mixture  of  mucus  and  the  secretions  of  the  numerous  glands 
which  open  into  this  cavity  ;  namely,  the  secretion  of  the  salivary 
glands.  By  hawking  and  coughing,  the  secretory  products  of 


Fig.  216.  The  same  submaxillary  gland  after  prolonged  irritation  of  the  nerves,  after  Heidenhain. 
O,  protoplasma  cells ;  b,  remains  of  the  mucous  cells. 

the  air-passages,  and  by  vomiting,  arrested  contents  of  the 
stomach,  as  well  as  remains  of  food  and  particles  of  dust,  may 
be  associated  with  these  essential  integrants.  On  examining 
the  parietes  of  the  oral  cavity,  especially  the  papillae  filiformes 


424 


SECTION    SEVENTEENTH. 


on  the  back  of  the  tongue  (Fig.  217)  and  the  gums  at  the  base 
of  the  crown  of  the  teeth,  they  are  found  to  be  covered  by  a 
sometimes  thinner,  sometimes  thicker,  slightly  brown,  fine  gran- 
ular covering,  which  contains,  together  with  decomposed  ani- 
mal substances,  the  filaments  and  fragments  of  a  lower  vege- 
table organism  from  the  order  of  the  Schizomycetes  fNageli). 
This  (the  Leptothrix  buccalis  of  Robin)  consists  of  a  confused 
mass  of  extremely  fine  filaments. 

The  gastric  furred  tongue,  when  in  a  rough  condition,  shows 
a  proliferation  of  the  familiar  epithelial  processes  of  the  papillae 

filiformes,  or,  when  the  surface  is 
smooth,  a  covering  composed  of 
luxuriant  epithelial  cells,  the  above- 
mentioned  vegetable  filaments  and 
mucous  corpuscles. 

The  substances  in  question  may 
be  readily  obtained  from  the  living 
body  for  examination,  by  scraping 
with  the  blade  of  a  knife.  To  un- 
derstand the  entire  arrangement,  a 
fresh  body  should  be  used  and  re- 
course be  had  to  vertical  sections 
after  a  previous  hardening. 

The  vegetable  organism  just 
mentioned  must,  in  consequence  of 

its  frequency,  be  designated  as  a  normal  occurrence.  Another 
vegetable  parasite  from  the  group  of  fungi,  Oidium  albicans, 
occurs  in  thrush  (magnet),  a  very  frequent  disease  of  the  earlier 
period  of  suckling  (fig.  218).  In  the  ordinary,  slighter  grades 
of  the  disease,  its  collections  appear  as  whitish,  later  as  grayish- 
yellow  plates,  sometimes  more  isolated,  sometimes  confluent, 
and,  in  high  degrees,  almost  covering  the  entire  oral  cavity, 
even  extending  down  into  the  oesophagus.  If  we  place  a  small 
portion  of  this,  mixed  with  water  or  some  alkaline  fluid,  under 
the  microscope,  we  see  much  broader,  jointed,  fungous  filaments 
(0),  with  spores  (b)  and  mycelium,  so  that  it  is  impossible  to  con- 
found them  with  the  Leptothrix  buccalis,  the  filaments  of  which 
are  so  fine. 


4Ki-t- 

Fig.  217.  A  papilla  filiformis  with  its 
epithelial  processes,  over  which  is 
spread  out  the  matrix  of  the  Leptothrix 
buccalis,  from  which  also  single  fila- 
ments are  growing  out. 


DIGESTIVE    ORGANS.  425 

A  drop  of  saliva,  placed  under  the  microscope,  shows  air- 
bubbles  entangled  in  it,  sometimes  in  smaller,  sometimes  in 
larger  numbers,  then  the  separated  pavement  epithelium  of  the 
oral  cavity  which  floats  about  in  the  fluid,  partly  hanging  to- 
gether in  shreds,  partly  isolated  (fig.  219),  and  either  unaltered 


Fig.  218.  Thrash  fungus,  Oidi-  Fig.  219.  Pavement  epithelium  of 

urn  albicans  of  the  nursing  child.  the  oral  cavity. 

o,  fungous  filaments ;  6,  spores  ; 
c,  pavement  epithelium  of  the 
mouth. 

in  appearance  or  having  already  undergone  maceration  to  a  cer- 
tain extent.  Finally,  the  salivary  corpuscles  are  noticed  as  an 
element  which,  though  never  absent,  still  varies  in  quantity. 
Fresh,  living  cells  ,of  this  kind  show,  with  a  higher  magnifying 
power,  a  distinct  dancing  movement  of  the  elementary  granules 
which  occur  in  their  bodies.  Consequently,  effete  salivary  cor- 
puscles, which  are  undergoing  decomposition,  no  longer  present 
this  movement  phenomenon. 

Filaments  of  cotton,  lint,  etc.,  remains  of  food — for  example, 
fibres  of  meat,  granules  of  starch,  particles  of  vegetable  tissue, 
fragments  of  milk,  appearing  in  the  form  of  fat-globules  and 
drops — form  adventitious  constituents  of  the  saliva. 

The  methods  for  examining  the  oesophagus  are  the  same  as 
those  for  the  oral  cavity,  and  may  therefore  be  omitted  here. 

The  investigation  of  the  stomach  is,  on  the  contrary,  of  higher 
importance.  In  its  examination  always,  when  possible,  avoid 
older  cadavers  and,  for  many  observations,  use  only  the  recently 
killed,  not  yet  cold  mammalial  animal.  Fine  sections  through 
the  soft  tissue  are  difficult  to  make,  but  very  easy,  on  the  con- 


426 


SECTION    SEVENTEENTH. 


trary,  through  the  frozen  parietes.  On  these  may  be  perceived, 
by  the  addition  of  indifferent  fluids,  the  peptic-gastric  glands  of 
the  mucous  membrane,  the  gland-cells,  and  finally  the  cylinder 
epithelium  of  their  apertures,  as  well  as  of  the  surfaces  lying 
between  them.  A  not  too  prolonged  immersion  in  a  J— J-  per 
cent,  solution  of  osmic  acid  has  recently  been  recommended  for 
these  delicate  cellular  coverings  (Ebstein).  The  addition  of 
dilute  alkalies  rapidly  dissolves  these  gland-cells,  so  that  the 
membranes  of  the  tubes  only  remain.  Hardening  methods 
(absolute  alcohol,  chromic  acid,  chromate  of  potash,  osmic  acid) 
are  necessary  for  the  more  accurate  study  of  their  arrange- 
ment, as  well  as  for  that  of  other  elements  lying  in  the  tissue 
of  the  mucous  membrane.  Injections  readily  succeed.  Either 


Fig.  220.  Vertical  section 
through  the  mucous  membrane  of 
the  human  stomach,  o,  super- 
ficial papillae;  &,  peptic-gastric 
glands. 


Fig.  221.    Three  human  peptic-gastric  glands. 


the  arteria  coaliaca  or  the  vena  portarum  are  to  be  selected 
in  smaller  creatures;  in  larger  animals  an  arterial  branch 
on  the  external  surface  of  the  stomach  is  to  be  used.  All 


DIGESTIVE    ORGANS.  427 

attempts  to  ascertain  the  presence  of  a  lymphatic  apparatus  per- 
meating the  mucous  membrane  have  been  thus  far,  on  the  con- 
trary, unsuccessful. 

To  obtain  fine  views  of  the  tubular-shaped  gastric  glands 
(fig.  220)  it  is  best  to  prepare  thin,  vertical  sections  from  the 
mucous  membrane  hardened  in  absolute  alcohol ;  they  are  to  be 
examined  in  glycerine,  without  the  addition  of  any  more 
strongly  acting  reagent.  The  simple  and  more  complicated 
tubular  glands,  as  well  as  the  several  varieties  of  cells  which 
line  them,  may  then  be  readily  recognized.  Fine  tingeing  con- 
stitutes an  important  accessory  for  further  details.  We  rec- 
ommend here  Heidenhain's  directions  for  carmine  and  aniline 
staining  (p.  155  and  157).  Fine  transverse  sections  are  natu- 
rally indispensable  for  other  conditions. 

.  One  form  of  the  gastric  tubes  (fig.  221)  bears  the  name 
of  peptic  glands.  At  the  present  time  we  can  with  certainty 
ascribe  the  production  of  the  pepsin  to  these  alone.  At  the 
first  view  their  compact  contents  appear  as  large  granular  cells 
(fig.  222). 

Recent  more  accurate  investigations  (Tleidenhain,  Rollett), 
however,  show  a  further  composition.  There  are  two  forms  of 
the  gland-cells  to  be  distinguished.  The  one,  smaller  and  more 
transparent,  usually  appears  to  line  the  whole  interior  of  the 
tube  in  a  coherent  layer ;  the  other,  larger  and  more  granu- 
lated, appears  more  externally  and  isolated.  The  latter  is  the 
peptic  cell  of  the  writers,  called  by  lieidenhain  "BdegzelU?  by 
Rollett,  "  delomorphous  "  cell.  The  smaller  continuous  form 
is  called  by  the  former  observer  the  "  hawptzefte"  by  the 
latter  the  "  adelomorphous "  cell.  Our  figure  223  represents 
the  condition  mentioned,  from  the  stomach  of  the  dog  (which 
is  especially  adapted  for  these  investigations). 

A  series  of  statements  made  by  lieidenhain  concerning  the 
condition  of  the  peptic-gastric  glands  in  the  condition  of  rest 
and  of  activity  is  extremely  interesting.  In  the  fasting  animal 
the  tubular  glands  appear  shrunken,  their  contours  are  smoother, 
and  their  kaupt-cells  are  transparent  (fig.  223,  1).  Several 
hours  after  the  reception  of  food  the  peptic-gastric  glands  pre- 
sent an  entirely  different  appearance  (2,  3).  They  are  swollen, 


428 


SECTION    SEVENTEENTH. 


the  walls  irregularly  dilated,  the  hauj}t-ce\\s  are  enlarged  and 
rendered  cloudy  by  their  finely  granular  contents.  Finally,  at 
a  later  period  (4-)  shrinking  has  again  taken  place,  the  haupt- 
cells  are  considerably  diminished  in  size,  but  are  also  very  rich 


Fig.   222.      Various  forms  of 
the  human  peptic  cells. 


Fig.  223.  Peptic-gastric  glands  of  the  dog,  after  Heidenhain,  the  peptic  cells  darkened  by 
means  of  aniline  blue.  1,  the  gland  of  the  fasting  animal ;  2,  portion  of  a  swollen  pne  in  the  first 
period  of  digestion  ;  3,  transverse  and  oblique  sections  of  the  same ;  4,  tubular  gland  at  the  end 
of  digestion. 

in  granular  matter.     Their  susceptibility  to  staining  is  conforma- 
ble therewith. 

If  the  thick  mucous  coating  which  usually  occurs  on  the 
inner  surfaces  of  the  stomach  of  herbivorous  animals,  espe- 
cially the  rodents,  be  examined  it  will  be  found  to  contain  a 
considerable  number  of  the  gland-cells  in  question,  part  of 


DIGESTIVE    OKGANS. 


429 


which  appear  quite  unchanged,  part  in  various  stages  of  decom- 
position, and  thus  constitute  a  surplus  of  the  ferment  bodies 
which  are  so  indispensable  for  gastric  digestion. 

Another  form  of  the  gland-cells  of  partly  simple,  partly 
branched  tubular  glands  (fig.  224,  1,  2),  the  so-called  gastric 
mucous  glands,  is  the  cylindrical,  such  as  occur  in  the  Lieber- 
klihn's  glands  of  deeper  portions  of  the  digestive  canal.  While, 
however,  the  cells  of  the  efferent  (occasionally  very  long)  por- 
tion of  the  gland  coincide  completely  with  the  cylindrical  epi- 
thelium of  the  gastric  surface,  shorter,  more  granular  cells,  which 
are  rendered  quite  cloudy  by  acetic  acid,  occur  at  the  fundus  of 
the  gland.  One  is  reminded  by  them  of  Heidenhain's  haupt- 
cells  in  the  peptic-gastric  glands.  Both  varieties  of  cylindrical 


Fig.  225.  Transverse  section  through  the 
gastric  mucous  membrane  of  the  rabbit, 
a,  tissue  of  the  mucous  membrane  ;  6,  trans- 
verse sections  of  empty  and  injected  blood- 
vessels, c ;  d,  spaces  for  the  peptic-gastrio 
glands. 


Fig.  224.  So-called  gastric  mucous 
glands.  1,  simpler  gland  from  the 
hog  ;  a,  the  cylindrical  epithelium  ; 
6,  lumen  ;  1*,  isolated  cells  ;  2,  com- 
pound tubular  gland  from  the  dog. 


cells  of  the  gastric  mucous  glands  also  act  differently  with 
regard  to  the  above-mentioned  methods  of  staining  with  car- 
mine and  aniline  blue.  The  proper  glandular  cell-elements  at 
the  fundus  of  the  tube  appear  rich  in  granules  during  gastric 
digestion  or  gastric  irritation,  and  poor  in  granules  in  the 
fasting  animal  (Ebstein).  Unfortunately,  no  agreement  has  yet 


430  SECTION    SEVENTEENTH. 

been  obtained  in  the  experiments  concerning  the  fermentative 
properties  of  these  cells  (1*). 

Horizontal  sections,  when  brushed  a  little,  show  the  ordinary 
fibrous  connective  tissue  of  the  mucous  membrane  between 
the  glands  (fig.  225).  It  is  as  a  rule  entirely  free  from  lymph- 
corpuscles.  From  existing  statements  of  accurate  observers  it 
is  not  to  be  doubted,  however,  that  they  may  under  certain  cir- 
cumstances obtain  a  more  reticular  character  in  man,  and  may 
produce  lymph-cells.  The  frequent  occurrence  in  many  per- 
sons of  scattered  lymphoid-follicles,  the  so-called  lenticular 
glands,  in  and  beneath  the  gastric  mucous  membrane,  is  also  an 
argument  in  favor  of  this  metamorphosis  of  the  tissue  of  the 
mucous  membrane. 

For  the  recognition  of  the  muscular  tunic  of  the  mucous 
membrane,  vertical  sections  from  the  fresh  mucous  membrane 
may  be  acted  on  for  10-20  minutes  by  the  30-35  per  cent,  so- 
lution of  potash,  or  thin  sections  may  be  made  from  good 
alcoholic  preparations  and  stained  with  carmine  (with  the  sub- 
sequent action  of  acetic  acid).  Schulze's  chloride  of  palladium 
method  with  carmine  tingeing,  and  Schwarz's  double  staining 
with  carmine  and  picric  acid,  deserve  recommendation  here,  as 
well  as  for  the  entire  digestive  apparatus.  The  immersion  of  the 
fresh  gastric  mucous  membrane  in  very  dilute  acetic  acid  or  pyro- 
ligneous  acid  also  deserves  to  be  mentioned.  These  two  fluids 
constitute  the  most  important  accessories  for  the  investigation 
of  the  gastric  nerves  which  contain  small  ganglia.  They  may  be 
readily  recognized  in  the  submucous  tissue,  but,  having  entered 
the  mucous  membrane  proper,  they  escape  further  observation. 

Pathological  changes  of  the  walls  of  the  stomach  are  of  rather 
frequent  occurrence. 

As  a  result  of  chronic  catarrh,  as  wrell  as  after  small  hemor- 
rhagic  effusions,  the  mucous  membrane  not  unfrequently 
assumes  a  slate  color  over  larger  or  smaller  places,  and  the  mi- 
croscope shows  an  embedment  of  black-pigment  molecules.  In 
slighter  degrees  of  the  disease  the  gastric  glands  are  found  to 
be  well  preserved ;  although  they  often  appear  distended  by 
large  masses  of  cells,  the  contents  of  the  latter  being  opaque 
(Forster).  In  such  conditions  the  mucous  membrane  is  not  un- 


DIGESTIVE    ORGANS.  431 

frequently  found  to  have  an  uneven  "  mainmillated "  surface, 
which  -is  dependent  partly  upon  lymphoid  follicles,  partly  on  a 
local  hypertrophy  of  the  mucous  membrane  and  its  glands,  and 
occasionally  also  upon  a  development  of  fat-lobules  in  the  sub- 
mucous  tissue.  Higher  degrees  may  assume  the  form  of  poly- 
pous protuberances.  A  new  formation  of  smooth  muscular 
tissue  may  also  take  place  from  the  muscular  tunic  at  the  pylo- 
rus, which  then  produces  an  annular  constriction  of  the  latter, 
and  has  formerly  been  frequently  erroneously  regarded  as  a 
gastric  carcinoma.  Vertical  sections  from  the  hardened  tissue 
would,  in  such  cases,  show  the  disposition  without  difficulty. 

The  microscopic  examination  of  vomited  matters  has,  thus  far, 
yielded  only  relatively  slight  results  for  the  purposes  of  the 
practical  physician. 

Among  them  (fig.  226)  appear,  first,  the  constituents  of  the  food 
which  has  been  taken.  These  are  natu- 
rally of  the  most  manifold  varieties, 
and  appear  partly  unchanged,  partly 
slightly  altered,  partly  commencing  to 
decompose  in  consequence  of  the  ac- 
tion of  the  lukewarm  gastric  fluid,  or 
in  various  stages  of  digestion  from  the 
fermentative  action  of  the  gastric 
juice.  At  the  same  time  it  should 

not  be  forgotten    tO    take    illtO  aCCOUnt        Fig.  226.  Elementary  constituents  of 
a  vomited  masses. 

the     textural    changes    which    have     «..  peptic  ceiis;  &,  cylindrical  epi- 

D  thehum;    c,  mucous  corpuscles;    d, 

already  been  caused  in  the  elements  pavement-ceiis  Of  the  oral  cavity ;«, 

^  sarcena  ventriculi ;    /,   Cryptococcus 

Of  the  food  by  itS  preparation.  cerevisiaj  :   g,  starch  bodies;  /*,  fat- 

•  r      r  drops ;  i,  muscular  filament. 

Thus  we.  meet  with  various  condi- 
tions of  the  granules  of  starch  (</),  which,  as  is  known,  have  a 
dissimilar  appearance  according  to  the  several  varieties  of  the 
starch  (rye,  wheat,  barley,  peas,  potatoes).  The  addition  of  iodine 
(p.  136)  serves  for  their  recognition,  if  the  observer  should  ever 
be  in  doubt.  Furthermore,  we  meet  with  the  greatest  variety 
of  vegetable  cells,  spiral  fibres,  and  other  structures  of  vegetable 
origin. 

If  we  proceed  to  the  examination  of  the  animal  food  we  find 
molecules  and  drops  of  fat  (h)  coming  from  milk  and  fat-tissue ; 


432'  SECTION    SEVENTEENTH. 

furthermore,  connective  tissue  parts  with  hyaline  interstitial 
substance,  but  unchanged  cells,  and  the  likewise  unaltered  elas- 
tic fibres.  Muscular  fibres  (i),  in  consequence  of  our  mode  of 
life,  constitute  a  very  general  constituent  of  vomited  masses  of 
food.  These,  in  consequence  of  the  free  gastric  juice,  frequently 
appear  in  the  stage  of  transformation  which  we  have  already 
mentioned  (p.  326),  as  the  effect  of  the  0.1  per  cent,  solution 
of  hydrochloric  acid,  that  is,  with  distinct  transverse  lines  and 
the  separation  into  plates  or  disks.  Pieces  of  cartilage  will  be 
more  rarely  found  in  matters  vomited  by  man,  and  still  less 
frequently  a  fragment  of  bone.  While  the  certain  recognition 
of  these  constituents  suffices  for  the  practitioner,  their  meta- 
morphoses present  an  interesting  phenomenon  for  the  histolo- 
gist  and  the  physiologist.  It  is  also  very  desirable  that  a  sys- 
tematic study  might  be  made  of  the  action  of  the  gastric  juice 
on  the  various  animal  tissues — a  research  which  could  be  readily 
instituted  with  artificially  prepared  gastric  juice. 

"With  these  constituents  of  the  food  which  has  been  taken  are 
also  associated,  as  admixtures  of  very  unequal  quantity,  the 
separated  epithelium  of  the  digestive  canal — pavement-cells  of 
the  oesophagus,  and  the  parts  lying  higher  (d),  cylindrical  cells 
of  the  gastric  mucous  membrane  (b) ;  likewise  the  cellular  ele- 
ments of  the  mucous  and  tubular  glands  (a),  frequently,  how- 
ever, visible  only  in  fragments ;  and  finally,  the  mucous  cor- 
puscles having  a  granular  appearance  (c). 

Pathological  conditions  of  the  organ  in  question  may  natu- 
rally associate  new  elements  with  the  vomited  matters. 

In  the  watery,  opalescent,  and  generally  sour  fluid  which  is 
vomited  in  so-called  pyrosis,  we  recognize  principally  epithelial 
cells  and  mucous  (salivary)  corpuscles.  Green  vomit  does  not 
show  anything  special  by  microscopic  examination.  The  color 
is,  as  is  known,  due  to  the  coloring  matter  of  the  bile. 

Large  numbers  of  mucous  corpuscles,  together  wTith  separated 
pavement  epithelium  from  the  oral  and  nasal  cavities,  may  also 
be  recognized  in  the  rice-water-like  substances  which  are  vomit- 
ed in  Asiatic  cholera.  One  notices,  on  the  contrary,  but  few 
other  cells,  such  as  those  of  the  gastric  glands  and  cylindrical 
epithelium. 


DIGESTIVE    ORGANS.  433 

In  the  brown  and  black  coffee-ground-like  masses,  such  as 
occur  in  certain  diseases,  gastric  hemorrhages,  gastric  carcinoma, 
and  yellow  fever,  the  color  is  caused  by  decomposed  blood  and 
hseniatine.  Here  one  meets  with  partly  more  normal,  partly 
changed  blood-cells,  lumps  of  decomposed  blood,  epithelial  and 
other  cells,  which  appear  saturated  with  hsernatine,  and  colored 
brown. 

Masses  vomited  during  abnormal  fermentative  processes  of 
the  gastric  cavity  show  interesting  microscopical  phenomena. 

In  fermenting  fluids,  as  well  as  in  bread,  a  fungus,  the  Cryp- 
tococcus  cerevisise,  consisting  of  oval  cells  (fig.  226  f\  occurs. 
From  our  mode  of  life,  we  frequently  receive  this  with  our  food, 
without  any  injurious  effects.  Under  certain  circumstances, 
however,  a  very  extraordinary  increase  of  these  cells  takes  place 
in  the  stomach,  and  the  discharged  matters  contain  large  num- 
bers of  them. 

Another  more  interesting  parasite,  though  more  obscure  as 
to  its  natural  history,  is  the  sarcena  ventriculi  (c\  discovered 
many  years  ago  by  J.  Goodsir.  This — very  probably  a  form  of 
Schizomycetes — consists  of  regularly  united,  cubical  aggrega- 
tions of  roundish  cells.  The  latter  are  found  united  in  series  of 
4,  8,  16,  32.  Definite  disturbances  of  the  gastric  functions  do 
not  coincide  with  the  occurrence  of  the  sarcina,  so  that  they  are 
of  no  pathological  importance. 

The  above-mentioned  thrush-fungus  of  the  nursing  child 
(fig.  218),  in  higher  degrees  of  the  disease  also  occurs  in  large 
quantities  in  the  stomach,  as  would  be  naturally  expected  from 
swallowing  the  masses  of  fungus. 

The  methods  of  examining  the  intestinal  canal  are,  for  the 
most  part,  the  same  as  have  been  mentioned  for  the  stomach. 

Concerning  the  cylindrical  epithelium  of  the  intestines,  and 
the  seam  which  is  permeated  by  porous  canals,  the  essentials 
have  already  been  mentioned  at  page  256.  Nevertheless,  we 
must  here  mention  a  structural  condition  which  has  recently 
been  more  accurately  investigated.  Together  with  the  ordinary 
cylindrical  cells  (fig.  227  &),  others  (#),  which  were  characterized 
by  varying  contents,  a  difference  of  form,  and  above  all  by  the 

absence  of  a  cell-membrane  at  the  upper  free  extremity,  were 
28 


434  SECTION    SEVENTEENTH. 

discovered  long   ago  at  more  or  less  regular  distances  from 

each  other,  and  varying  in  number. 
The  structures  in  question  resemble 
sometimes  a  pear,  sometimes  a  wide- 
bellied  drinking  glass.  F.  E.  Schulze 
met  with  them  throughout  the  entire 
intestinal  canal,  and  in  its  tubular 
Mg.  2*r.  ceiis  of  the  epithelium  of  glands  in  the  vertebrate  animals,  in 

the   P*K»geB  of   the   lungs,  and  in 
6,  cylindrical  epithe-    creatures  living  in  water  (fishes  and 
amphibia),   on   the   skin.       He  has 

given  them  the  name  of  "  Becker zellen "  (cup-shaped  cells), 
and  declares  them  to  be  mucous-secreting  structures. 

A  recently  killed  animal  is  to  be  used  for  their  investigation, 
and  the  examination  made  either  immediately,  with  the  addi- 
tion of  indifferent  media,  such  as  iodine-serum,  or  after  immer- 
sion for  several  days  in  Muller's  fluid.  Nitrate  of  silver  lias  also 
been  employed. 

Mucous-  and  pus-corpuscles  penetrate  into  the  interior  of  the 
cylindrical  epithelial  cells,  as  probably  do  also  in  the  rabbit  the 
still  so  enigmatical  Psorosperms  (Klebs,  Frey,  and  others),  and 
not  only  into  the  cylindrical  cells  of  the  small  intestines,  but 
also  into  those  of  Lieberkiihn's  glands  as  w^ell  as  those  of  the 
biliary  passages. 

The  resorption  of  the  chyle-fat  by  the  cylindrical  cells  of  the 
intestinal  villi  may  be  observed  in  fresh  and  hardened  speci- 
mens. The  handsomest  appearances  may  be  obtained  in  the 
smaller  mammalia  by  the  previously  mentioned  injection  of 
milk.  Seldom,  and  only  by  a  rare  chance,  can  the  body  of  a 
human  being  who  has  suddenly  died  during  the  digestion  of  fat 
be  obtained.  The  examination  must  naturally  be  made  as 
soon  as  possible,  as  the  decomposition  which  takes  place  so 
rapidly  in  the  digestive  canal  obliterates  the  delicate  textural 
relations.  Older  cadavers  are  entirely  useless,  as  the  fine  chyle 
molecules  in  the  intestinal  villi  usually  flow  together  into  large 
drops,  and  nothing  remains  of  the  cylindrical  epithelium. 

The  contents  of  the  Lieberkiihn's  glands  also  show  beauti- 
fully and  distinctly  in  quite  fresh  intestines,  by  the  addition  of 


DIGESTIVE    OEGANS.  435 

indifferent  fluids ;  likewise  in  alcohol  and  chromic  acid  prepa- 
rations. Their  cylindrical  gland-cells  (between  which,  as 
Schulze  saw,  cup-shaped  cells  occur)  are  also  quite  perishable, 
so  that  one  often  meets  with  only  the  finely  granular,  nucleated 
contents  of  the  tubular  glands  as  an  artefact. 

Hardening  methods  are  to  be  employed  for  all  the  remaining 
structural  conditions.  The  drying  process  was  formerly  em- 
ployed, in  consequence  of  the  poverty  of  the  technique  of  that 
period.  There  is  one  investigation,  the  study  of  the  Brunner's 
glands  (fig.  228),  for  which  we  would  still  recommend  this  pro- 
cedure, modified  by  previously  boiling  the  tissue  in  vinegar.  In 


Fig.  228.  Human  Brunner's  gland. 

fact,  handsome  preparations  may  thus  be  obtained,  and  the 
marvellously  elegant  ramifications  of  the  efferent  passages  may 
often  be  followed  in  the  interior  of  the  body  of  the  racemose 
gland,  especially  in  thin  vertical  sections.  Nevertheless,  at  the 
present  day  the  same  purpose  is  also  fulfilled  by  hardening  with 
chromic  acid,  chromate  of  potash,  and  especially  with  absolute 
alcohol,  methods  which,  together  with  that  of  freezing,  consti- 
tute the  most  important  accessories  for  the  remaining  structures 
of  the  intestinal  canal.  With  them,  one  may  even  recognize, 
the  same  as  in  the  mucous  glands  of  the  oral  cavity,  the  oblong 
form  of  the  acini  and  the  cylindrical  form  of  the  cells  of  the 
Brunner's  glands  (Schlemmer). 


436 


SECTION   SEVENTEENTH. 


Tingeing  and  brushing  may  be  added  according  to  necessity 
for  the  further  study  of  the  intestines. 

The  tissue  of  the  mucous  membrane  (fig.  229)  is  differently 
constituted  from  that  of  the  stomach. 


Fig.  229.  From  the  small  intestine  of  the  rabbit,  a,  tissue  of  the  mucous  membrane  ;  6,  lymph- 
canal;  c,  spaces  for  the  Lieberkiihnian  glands;  d,  transverse  section  of  the  Lieberkiihiiian 
glands  filled  with  cells. 

In  the  latter  organ  we  meet  with  ordinary  fibrous  connective 
tissue.  A  looser  reticulated  substance,  with  nuclei  in  individual 
nodal  points,  has  here  taken  its  place.  Lymphoid  cells  (a)  lie 
embedded  in  the  meshes,  and  are  especially  numerous  in  the 
small  intestine.  We  have  here,  therefore,  a  variety  of  the 
reticular  lymph-cell  producing  connective  substance,  which  is 
similar  to  the  framework  substance  of  the  lymphatic  glands 
(comp.  p.  270).  The  tissue  of  the  intestinal  mucous  membrane, 
however,  bears  a  character  of  irregularity  and  mutability  which 
we  do  not  meet  with  in  the  lymphatic  glands,  at  least  under 
normal  conditions.  This  tissue  becomes  condensed  into  a  more 
homogeneous  membranous  layer  around  the  glandular  tubes 
at  the  surface  of  the  intestinal  villi,  and  also  forms  the  limiting 
layer  of  the  lymphatic  canals  which  pass  through  the  mucous 
membrane.  In  places,  especially  toward  the  surfaces  of  the 
larger  blood-vessels  and  lymphatics,  the  tissue  of  the  mucous 
membrane  may  assume  a  different  appearance,  and  may  even 
permit  of  the  recognition  of  the  wavy  fibrous  bundles  of  the 
ordinary  connective  tissue.  On  the  other  side,  however,  as  will 
soon  be  shown,  the  tissue  in  question  passes  continuously  over 


DIGESTIVE    OKGANS. 


437 


into  the  regular  reticulated  framework  of  the  solitary  arid  Peye- 
rian  follicles. 

In  conformity  with  this  is  a  textural  condition  which  is  inter- 
esting for  the  nature  of  connective  tissue  in  general.  AYithin  a 
certain  space  we  perceive,  at  slight  distances  from  each  other, 
the  one  variety  of  connective  tissue  becoming  metamorphosed 
into  the  other,  occurrences  which,  as  is  known,  pathological  his- 
tology has  so  frequently  shown  to  take  place  temporarily  after 
each  other. 

The  conditions  which  have  just  been  mentioned  are  related 
first  of  all  to  the  small  intestine  of  man,  the  mammalia,  and 
birds.  The  tissue  of  the  mucous  membrane  of  the  large  intes- 
tine appears  to  be  modified  more  in  accordance  with  the  fibrous 
connective  tissue,  and  is  usually  poorer  in  lymph-cells. 

Brushing  the  reticular  tissue  of  these  mucous  membranes  may 
be  accomplished  with  tolerable  facility,  and  in  young  creatures 
the  recognition  of  the  nuclear  formations  is  not  difficult.  In 

O 

those  which  are  older  the  number  of  the  nuclei  is  indeed  dimin- 
ished. 


Fig.   230.     Lieberkiihnian 
glands  of  the  cat. 


Fig.  231.  Tubular  glands  of 
the  large  intestine  of  the  rab- 
bit after  treatment  with  caubtic 
soda. 


Tig.  232.  Apertures  of  the 
glands  of  the  large  intestine 
(representing  at  the  same 
time  the  transverse  sections 
of  deeper  lying  portions  of 
the  glands)  from  the  rabbit. 


The  Lieberkuhnian  glands  of  the  small  intestine  (fig.  230) 
and  the  tubular  glands  of  the  large  intestine  (fig.  231),  which 
are  quite  identical  with  the  former,  repeat  in  their  arrangement 


438 


SECTION    SEVENTEENTH. 


and  frequency  the  conditions  of  the  stomach.  They  are  to  be 
examined  with  the  same  accessories.  On  thin  horizontal  sec- 
tions of  freshly  immersed  parts  one  may  become  convinced  of 
the  epithelium-like  arrangement  of  the  cells,  and  see  how  these, 
conically  sloped  towards  each  other,  turn  their  bases  outwards 
and  their  narrow  terminal  surfaces  towards  the  axis  of  the  tube 
(tig.  232).  How  far  they  are  provided  with  a  special  membrana 
propria  to  form  a  line  of  demarcation  between  them  and  the 
surrounding  tissue  of  the  mucous  membrane  appears  still  to 
require  a  more  accurate  investigation. 


Fig.  233.  Small  intestine  of  the  cat,  in  vertical 
section,  o,  the  Lieberkiihnian  glands  ;  6,  the  in- 
testinal villi. 


Fig.  234.  An  intestinal  vil- 
lus.  a,  the  cylindrical  epithe- 
lium with  its  thickened 
seam  *  &,  capillary  network ; 
c,  smooth  muscular-tissue ; 
rf,  central  chyle- vessel. 


The  muscular  tunic  of  the  mucous  membrane  is  brought  to 
view  by  means  of  the  same  accessories  as  were  used  for  that  of 
the  stomach. 

Peculiar  phenomena  are  presented  by  the  intestinal  yilli 
which  are  met  with  in  the  shape  of  variously-formed  projections, 
pressed  closely  together  in  large  numbers  over  the  whole  sur- 
face of  the  small  intestine  (Fig.  233,  #). 


DIGESTIVE    OEGANS.  439 

Their  tissue  (fig.  234)  bears  the  same  character  as  that  of  the 
remainder  of  the  mucous  membrane,  and  is,  as  was  remarked, 
membranously  thickened  at  the  outer  surface,  as  well  as  towards 
the  chyle  vessel  (d)  which  passes  through  its  axis.  In.  birds  I 
succeeded,  years  ago,  in  bringing  to  view  a  distinctly  reticular 
external  surface  (as  on  the  surface  of  a  lymphatic  gland-follicle) 
with  the  greatest  certainty.  Eberth  also  found  the  same  in  the 
goose,  and  was  able  to  recognize  a  similar  condition  of  the  sur- 
face of  the  villi  in  the  mammalia  and  in  man.  The  intestinal 
villi  of  the  rat  are  best  adapted  for  this  purpose.  Hardening 
for  a  month  in  Miiller's  eye-fluid  has  been  recommended  by 
that  investigator.  Longitudinally  arranged  smooth  muscular 
cells  (c)  also  occur  embedded  in  the  tissue  of  the  villi,  and  give 
these  organs  their  vital  contractility,  which  has  been  known  for 
a  long  time  and  which  is  so  important  for  the  onward  move- 
ment of  the  chyle. 

Horizontal  sections  of  the  villi  may  be  made  from  well-hard- 
ened intestines  by  means  of  a  very  sharp  razor  with  tolerable 
facility ;  I  find  it  difficult,  on  the  contrary,  to  obtain  a  good 
vertical  section,  even  from  the  voluminous  villi  of  larger  mam- 
malia, whether  the  dried  or  the  hardened  intestine  be  employed. 

The  submucous  tissue  is  to  be  investigated  with  the  customary 
methods.  The  accessories  which  have  been  already  mentioned 
(p.  342)  serve  for  the  examination  of  the  ganglionic  plexuses 
which  occur  here  (figs.  171,  172). 

Their  arrangement  is  to  be  studied  partly  on  vertical  sections, 
partly  on  surface  views  of  the  submucous  tunic  from  which  the 
muscular  and  mucous  membranes  have  been  separated. 

The  muscular  tunic  is  to  be  examined  according  to  the  direc- 
tions previously  given  for  that  tissue  (p.  313). 

The  remarkable  ganglionic  plexus,  discovered  by  Auerbach 
between  the  circular  and  longitudinal  muscular  layers  of  the 
intestine,  has  also  been  noticed  at  the  nervous  system  (p.  343). 

Injections  of  the  blood-vessels  of  the  intestinal  canal  succeed 
with  such  relative  facility  (in  the  smaller  creatures,  by  the  coeliac 
and  mesenteric  arteries  as  well  as  by  the  portal  vein  ;  in  larger 
ones,  by  the  arterial  and  venous  branches,  after  the  ligation  of 
those  which  supply  the  neighboring  districts),  and  afford  such  a 


440 


SECTION    SEVENTEENTH. 


permanent  landmark,  that  they  should  never  be  neglected.  A 
capillary  network  encircles  the  tubular  glands  with  an  abundant, 
extended,  reticular  formation  in  the  same  manner  as  in  the 
stomach,  so  that  there,  where  the  surface  of  the  mucous  mem- 
brane remains  smooth,  the  arrangement  is  quite  the  same.  Our 
fig.  235,  which  presents  the  capillary  network  of  the  gastric  mu- 


Fig.  235.  Semi-diagrammatic  figure  of  the 
rascular  arrangement  in  the  gastric  mucous 
membrane  (representing  at  the  same  time 
that  of  the  colon). 


Fig.  236.  The  vascular  net- 
work of  an  intestinal  villus  of  the 
hare,  with  the  arterial  trunk,  &, 
the  capillary  network,  c,  and  the 
venous  branches,  a. 


cous  membrane  in  vertical  section,  may  also  be  regarded  as  a 
figurative  representation  of  the  blood-vessels  in  the  deeper  por- 
tions of  the  colon. 

There,  however,  where  projections,  papillae,  and  villi  occur — 
and  this  is  the  case  for  the  entire  small  intestine,  as  also, 
occasionally,  for  portions  of  the  large  intestine — we  meet  with 
corresponding  modifications  of  the  vascular  arrangement.  In 
the  intestinal  villi  especially,  the  latter  become  very  character- 
istic and  elegant.  There  is  here  a  so-called  looped  network, 
that  is,  two  or  more  larger  trunks  pass  over  into  each  other  in 
a  loop-like  manner  at  the  summit  of  the  villus,  and  are  united 


DIGESTIVE    OEGANS. 


441 


in  their  course  by  an  intermediate,  more  circular  meshed  net- 
work. In  larger  villi,  as  our  fig.  236  shows,  the  arrangement 
may  become  considerably  complicated ;  in  small  specimens, 
those  of  the  mouse,  for  instance,  it  remains  much  more  sim- 
ple. 

The  capillary  network  always  lies  in  the  peripheral  portion 
of  the  villus,  so  that  the  central  portion  is  occupied  by  the 
lacteal  vessel  which  is  soon  to  be  described. 

The  blood  readily  remains  in  this  vascular  district,  so  that 
those  who  shun  the  trouble  of  an  artificial  injection  may  obtain 
quite  handsome  views  of  the  capillaries  of  the  villi  from  the 
body  of  an  animal  which  has  been  killed  several  hours  pre- 
viously by  strangulation. 

The  villus-like  projections  which  may  make  their  appearance 
in  the  large  intestine,  such,  for  instance,  as  occur  in  remarkable 
perfection  in  the  upper  portion  of  the  rabbit's  colon,  have  a 
similar  arrangement  of  the  blood-vessels,  but  differ  completely 
from  the  glandless  villi  of  the  intestines,  by  being,  like  the 
smoothly  spread  mucous  membrane  of  the  colon,  permeated 
by  glandular  tubes  in  close  ap- 
position. 

Finally,  as  regards  the  lym- 
phatics of  the  intestinal  canal, 
or  the  so-called  lacteals  of  these 
parts,  much  may  be  recognized, 
even  without  injections,  in  bodies 
in  which  the  digestion  of  fat  has 
commenced,  and,  in  fact,  in 
former  times,  many  observers 
have  obtained  valuable  informa- 
tion in  this  way.  The  accumu- 
lation of  chyle  may  be  observed 
with  facility  in  the  axis  of  the 
intestinal  villi  (fig.  237),  and 
with  somewhat  greater  difficulty  the  vessels  filled  with  fat  of 
the  mucous  membrane  and  sub-mucous  layers  (p.  394).  A 
suitable  medium  for  rendering  such  preparations  transparent 
is  still  wanting,  and  it  is  also  impossible  to  keep  them  in  a 


Pig.  237.  Intestinal  viUns  of  a  kid,  killed 
during  digestion,  with  the  lacteal  vessel  in 
the  axis. 


442  SECTION   SEVENTEENTH. 

moist  condition  for  a  long  time.  My  attempts,  at  least,  have 
been  entirely  frustrated. 

The  artificial  injection  by  means  of  the  puncturing  method 
was  therefore  a  great  improvement,  and  has,  within  a  few 
years,  increased  our  knowledge  of  the  lymphatics  of  the  intes- 
tinal canal  considerably.  I  believe  that  I  have  simplified  and 
facilitated  the  procedure  essentially  by  the  employment  of  the 
cold-flowing  transparent  mixtures. 

These  injections  succeed  with  greater  or  lesser  facility,  and 
occasionally  only  with  difficulty,  according  to  the  frequency  and 
extent  of  the  lymphatic  passages  and  lymphatics  with  valves 
which  lie  in  the  submucous  tissue.  The  small  intestine  of  the 
sheep  forms  a  very  favorable  object,  as  the  submucous  layer  is 
occupied,  or  rather  constituted,  by  a  surprisingly  large  number 
of  very  extensive  lacteals.  The  rabbit  must  also  be  designated 
as  an  animal  adapted  for  these  investigations,  but  the  thinness 
of  the  intestinal  parietes  renders  the  introduction  of  the  fine 
canules  somewhat  difficult.  The  procedure  succeeds  with  less 
facility,  in  consequence  of  the  narrowness  and  greater  sparsity 
of  the  lymphatics,  in  the  calf  and  the  hog,  the  dog  and  the  cat ; 
still  less  in  man,  although,  with  some  perseverance,  one  may 
also  succeed  with  infantile  as  well  as  (quite  fresh)  adult  bodies. 

With  such  intestines  as  are  difficult  to  manage,  one  may 
commence  with  the  Peyerian  follicles,  which  are  generally 
easier  to  inject,  and  thus  from  them  fill  the  neighboring  portions 
of  the  small  intestines  with  their  villi.  In  the  sheep  and  rabbit, 
on  the  contrary,  where  the  canule  is  well  introduced,  a  practised 
hand  almost  always  succeeds  in  forcing  the  mass  over  more  con- 
siderable surfaces.  Filling  the  lymphatics  of  an  entire  intes- 
tine of  the  sheep,  by  means  of  a  series  of  individual  injections, 
of  which  Teichrnann  speaks,  is,  in  fact,  no  great  proof  of  skill. 

It  would  lead  us  too  far,  were  we  here  to  describe  more 
minutely  the  relative  arrangements  of  the  horizontal  lymphatic 
plexuses  in  the  submucous  tissue,  the  vessels  which  pass  from 
them  into  the  muscular  tunic,  as  well  as  the  canals  which  pass 
up  between  the  tubular  glands  and  frequently  reunite  in  a 
plexiform  manner  (fig.  238  d).  In  the  intestinal  villi,  which 
vary  considerably  in  form  and  size,  being  lon^  and  thin,  and 


DIGESTIVE    OEGANS. 


443 


also  quite  broad  and  low,  there  are  lacteal s  of  varying  diameter 
with  csecal  extremities ;  in  the  first  case  they  are  single  (#),  in 
the  latter,  double  (&)  or  manifold  (c).  They  may  then  pass  into 
each  other  at  the  extremity  of  the  villas  in  an  arched  manner 


Fig.  238.   Vertical  section  through  the  human  ileum.    a,  intestinal  villi  with  single;  &,  with 
double ;  c,  with  triplicate  lacteals  ;  d,  lacteals  of  the  mucous  membrane. 


(<?),  or  still  maintain  the  independent  csecal  termination  (I). 
Transverse  branches  occur  more  frequently  in  the  deeper  por- 
tions of  these  more  complicated  lymphatics. 

The  injection  of  the  lymphatics  in  the  large  intestines,  that 
is,  in  their  mucous  membrane,  is  much  more  difficult  to  accom- 
plish. Their  occurrence  is  considerably  less  frequent,  and  the 
entire  arrangement  is  quite  variable  in  the  different  animals. 
Horizontal  reticulations,  passing  through  the  mucous  membrane 
with  short  knotty  vertical  passages,  and  level  ramifications  pass- 
ing  along  the  base  of  the  mucous  membrane  with  longer  canals, 
ascending  at  right  angels,  etc.,  also  occur.  These  lymphatics, 
which  have  essentially  increased  our  knowledge  of  the  processes 
of  absorption  in  the  intestinal  canal,  are  at  present  recognized 
in  the  ruminantia,  the  rodentia,  and  the  carnivora.  In  man 
(where  they  are  certainly  not  wanting),  the  experimental  proof 
of  their  presence  has 'not,  as  yet,  been  adduced. 

Have  these  lymphatics  of  the  intestine  a  special  vascular 
wall,  or  are  they  merely  cavities  bounded  by  connective  tissue  \ 

Recent  investigations  leave  no  further  doubt  that  beneath  the 


444  SECTION    SEVENTEENTH. 

serous  coverings,  and  in  the  muscular  layers  of  the  intestinal 
canal,  true  "  vessels  "  contain  the  chyle.  Their  knotty  appear- 
ance, caused  by  the  valves,  speaks  in  favor  of  this,  and  the 
walls  are  also  recognizable  after  the  connective  tissue  has  been 
rendered  transparent  by  means  of  acetic  acid,  pyroligneous 
acid,  etc.  In  part,  perhaps  in  most  of  the  mammalia,  this 
texture  is  still  maintained  in  the  lymphatics  of  the  submucous 
tissue,  while  in  others  there  is  even  here  a  formation  of  passa- 
ges with  lacunae,  that  is,  vessels  without  an  independent  vascu- 
lar wall.  Throughout  the  mucous  membrane  proper,  on  the 
contrary,  it  is  certain  that  only  the  latter  are  present. 

They  are  all,  nevertheless,  lined  with  the  peculiar  vascular  cells 
(see  p.  393).  These  lymphatics  are  therefore  bounded  by  a  very 
thin  but  entirely  connected  epithelium,  and  this  investment  is 
so  accurate  as  to  serve  the  same  purpose,  at  least  for  the  normal 
condition,  as  any  vascular  membrane.  Not  a  granule  of  the 
injection  mass  passes  into  the  adjacent  tissue  without  a  rupture. 
We  have  frequently  injected  the  small  intestines  with  the  finest 
mixtures  under  a  high  degree  of  pressure,  so  that  the  ducts  of 
the  intestinal  villi,  being  considerably  distended,  compressed 
the  spongy  tissue  of  the  latter  powerfully,  but  even  then  not  a 
molecule  of  the  injection  mass  passed  into  the  tissue.  That,  on 
the  contrary,  an  individual  immigration  into  the  lymphatics  of 
the  relatively  gigantic  lymph-corpuscles,  such  as  are  produced 
in  such  abundance  by  the  reticular  tissue  of  the  mucous  mem- 
brane, may  occasionally  take  place  is  evident.  Nevertheless, 
according  to  our  views,  these  cells  of  the  intestinal  mucous 
membrane  are,  under  normal  conditions,  without  a  future  ;  they 
arise  and  disappear  in  the  meshes  of  the  reticular  tissue.  On 
the  other  hand,  the  possibility  cannot  be  denied,  that  in  morbid 
processes  a  more  plentiful  transmigration  into  the  lymphatic 
current  may  take  place. 

Lymphatic  follicles  are  to  be  found,  although  varying  in 
quantity,  in  the  intestinal  canals  of  all  of  the  higher  vertebrates 
and  of  man.  They  occur  partly  isolated  or  in  very  small 
groups,  and  are  then  called  solitary  follicles  ;  they  are  also,  in 
part,  united  into  larger  collections  and  form  the  plaques  of  the 
Peyerian  glands. 


DIGESTIVE    ORGANS.  445 

The  latter  structures  are  most  plentiful  in  the  lower  portions 
of  the  small  intestine,  but  may  also — and  this  is  a  regular 
occurrence  in  many  mammalia — be  met  with  in  the  large 
intestines.  Generally  the  isolated  follicles  also  show  similar 
conditions. 

The  structures  with  which  we  are  occupied,  especially  the 
Peyerian  glands  which  are  the  most  thoroughly  understood,  are 
embedded  in  the  mucous  membrane  and  the  submucous  tissue. 


Fig.  239.    Vertical  section  through  a  fresh  Peyer's  patch  of  the  ileum  from  the  rabbit,    a,  in- 
testinal villi ;  &,  c,  follicles. 


Thus  we  see  in  the  vertical  section  of  the  small  Peyer's  patch 
of  a  rabbit  (fig.  239)  the  bases  of  these  follicles  (5,  c)  with  a 
globular  form  in  the  submucous  layer. 

Other  follicles  are  much  higher  a'nd  more  slender,  frequently 
assuming  an  appearance  resembling  the  sole  of  a  shoe,  and  are 
accompanied  by  an  increased  thickness  of  the  mucous  mem- 
brane and  submucous  tissue. 

At  an  earlier  period,  which  was  poor  in  methods  of  investi- 
gation, the  study  of  these  organs  was  difficult,  so  that  notwith- 
standing the  interest  awakened  by  the  participation  of  these 
structures  in  diseases,  especially  those  of  a  typhoid  nature,  our 
knowledge  of  them  could  not  be  made  to  progress  properly. 
At  the  present  time,  the  hardening  methods,  especially  the  im- 
mersion in  alcohol  or  chromic  acid  (drying  is  not  so  good)  are 
conducive  to  the  purpose.  With  these  must  naturally  be  asso- 
ciated the,  in  general,  not  easy  (complete)  injection  of  the 


446 


SECTION    SEVENTEENTH. 


blood-vessels  and  the  sometimes  easier,  sometimes  more  difficult 
injection  of  the  lymphatics. 

The  Peyerian  follicle  (fig.  240)  consists,  as  was  remarked,  of 
a  sometimes  more  globular,  sometimes  more  oblong  basis  por- 
tion (f)  extending  freely  into  the  submucous  tissue.  In  many 
creatures  there  is  a  system  of  connective-tissue  partition  walls 
between  the  basis  portions.  Secondly,  we  find  the  follicle  (cor- 
responding to  the  entire  form)  projecting  freely  into  the  intes- 


Fig.  240.  Vertical  section  through  a  human  Peyer'a  patch,  with  its  lymphatics  injected,  a,  in- 
testinal villi  with  their  lacteals ;  &,  Lieberkiihnian  glands ;  c,  muscular  layer  of  the  mucous  mem- 
brane ;  d,  apex  of  the  follicle ;  <?,  middle  zone  of  the  follicle ;  /,  basis  portion  of  the  follicle  ;  #,  con- 
tinuation of  the  lacteals  of  the  intestinal  villi  into  the  mucous  membrane  proper;  A,  reticular 
expansion  of  the  lymphatics  in  the  middle  zone ;  i,  their  course  at  the  base  of  the  follicle ;  k,  con- 
tinuation into  the  lymphatics  of  the  submucous  tissue ;  Z,  f ollicular  tissue  in  the  latter. 


tinal  canal,  with  a  sometimes  higher,  sometimes  flatter  apex  (d). 
These,  covered  with  cylindrical  epithelium,  are  surrounded  by 
more  or  less  prominent  elevations  of  the  mucous  membrane, 
which  are  generally  furnished  with  villi  (a  a). 

Between  the  apex  and  base  a  middle  zone  (e)  remains.  In  it 
the  demarcation  of  the  two  follicular  portions  is  wanting.  In 
yertical  and  horizontal  sections  it  is  seen,  on  the  contrary,  how 
in  this  middle  strata  all  the  follicles  of  one  plaque  pass  into 
those  of  another,  and  then  how  this  zone  is  continued  uninter- 


DIGESTIVE    OEGA^S.  447 

ruptedly  into  the  adjacent  tissue  of  the  mucous  membrane 
(I).  This  is  the  metamorphosis  of  the  reticular  connective  tis- 
sue of  the  mucous  membrane  into  the  reticular  framework  of 
the  lymphatic  gland  follicle,  of  which  we  have  already  spoken 
on  a  previous  page. 

Here  also  the  network  of  the  follicle  (fig.  241  J)  is  essentially 


Fig.  241.  The  tissue  of  the  Peyerian  follicle  of  an  adult  rabbit,  exposed  by  brushing,    a,  capil- 
lary vessels  ;  b,  reticular  framework ;  c,  lymph  corpuscles. 

the  same  as  occurs  in  the  large  lymphatic  glands ;  in  young 
bodies  it  is  a  cellular  reticulation,  in  older  ones  it  consists  more 
of  trabeculse  with  shrunken  nuclei  in  individual  nodal  points. 
Towards  the  periphery  of  the  basis  portion  the  tissue  assumes  a 
more  finely  reticulated  character  (as  also  occurs  towards  the  in- 
vesting spaces  of  the  follicles  of  the  lymphatic  glands) ;  in  the 
central  portions,  on  the  contrary,  the  meshes  are  not  unfre- 
quently  larger. 

The  blood-vessels  of  the  Peyerian  glands  have  recently  been 
frequently  described,  so  that  it  must  appear  superfluous  to  al- 
lude to  them  more  thoroughly  again.  Only  the  remark,  together 


448 


SECTION    SEVENTEENTH. 


with  several  examples,  may  here  find  place,  that  a  non-vascular 
central  portion  of  the  follicle  does  not,  as  a  normal  occurrence, 
exist.  Incomplete  injections,  it  is  true,  give  frequently  enough 


Fig.  242.  Vertical  section  through  an  injected  Peyerian  capsule  of  the  rabbit,  with  the  capillary 
network  of  the  same,  a,  the  larger  lateral  vessels,  &,  and  those  of  the  intestinal  villi,  c. 

the  false  image  of  capillary  loops  in  the  internal  portions  of  the 
follicle.  Our  figures  242  and  243  represent  this  arrangement 
of  the  vessels  in  a  small  Peyerian  patch  of  the  rabbit,  from  a 


Fig.  248.  Transverse  section  through  the  equatorial  plane  of  three  Peyeriau  capsules  of  the  same 
animal,    a,  the  capillary  network ;  &,  the  larger  annular-shaped  vessels. 


DIGESTIVE    ORGANS.  449 

very  complete  injection  mounted  dry.  We  have  also,  in  addi- 
tion, accurately  re-examined  the  arrangement  in  moist  speci- 
mens from  a  series  of  consecutive  sections. 

Good  injections  of  the  lymphatics  teach  the  following: — The 
lymphatic  vessels  (iig.  240,  #,  a)  which  return  from  the  intes- 
tinal villi  (the  so-called  lacteals)  form  a  reticulum  (g)  around  the 
tubular  glands  (l>)  wrhich  occur  in  the  villous  elevations,  and 
this  is  continuous  with  a,  network  of  reticularly  enclosed  vessels 
(h)  which  surrounds  the  middle  zone  of  each  follicle.  The  lat- 
ter then  open  either  into  a  simple  investing  cavity  which  sur- 
rounds the  basis  portion  like  a  shell  (rabbit,  sheep,  calf),  exactly 
similar  to  that  of  the  alveolus,  or  this  is  replaced  by  a  network 
of  separated  passages  and  lacunse  encircling  the  basis  of  the 
follicle  in  a  similar  manner,  so  that  this  portion  of  the  Peyerian 
follicle  (A,  *)  appears  like  a  toy-ball  around  which  a  thread  is 
wound  (as  in  man,  the  dog,  and  the  cat).  From  the  latter  sys- 
tem of  vessels  (or  from  the  simple  investing  space)  finally  arise 
the  efferent  lymphatics  of  the  submucous  layer  (£). 

The  reader  will  comprehend  that  follicles  of  the  latter  variety 
are  more  difficult  to  inject  than  those  of  the  first  form  with  the 
simple  shell-like  investing  spaces. 

The  vermiform  process,  as  well  as  the  small  and  scanty 
caecum  of  many  camivora  consists,  in  a  remarkable  manner,  of 
only  a  closely  crowded  collection  of  follicles.  The  processus 
vermiformis  of  man  and  of  the  rabbit  represents,  in  fact,  a 
Peyerian  plaque  which,  largely  extended,  forms  an  entire  por- 
tion of  intestine.  Teichmann  succeeded  in  injecting  them  in. 
man  ;  the  injection  of  the  vermiform  process  of  the  rabbit  is  a 
mere  child's  play,  and  the  entire  organ  deserves  to  be  most  ur- 
gently recommended  to  any  one  who  desires  to  study  the  Pey- 
erian follicles. 

Numerous  pathological  metamorphoses  of  the  intestines  be- 
come objects  of  microscopic  investigation.  The  same  methods 
which  we  have  mentioned  in  the  investigation  of  the  normal 
structures  are  generally  employed.  It  should  be  made  a  rule  to 
obtain  the  freshest  possible  objects,  as  the  decomposition  which 
soon  commences  changes  the  soft  tissues  in  such  a  manner  as  to 
render  them  unintelligible.  The  pathological  new  formations 
29 


450  SECTION    SEVENTEENTH. 

in  the  intestinal  canal  are,  in  general,  the  same  as  in  the 
stomach.  Thus  we  meet  with  similar  pigmentations,  connec- 
tive-tissue productions,  lipomata,  etc.  Carcinomatous  tumors 
occur  in  the  large  intestines,  especially  in  the  rectum.  Tuber- 
cles, on  the  contrary,  are  met  with  chiefly  in  the  ilenm,  less 
frequently  in  the  jejunum  and  colon.  It  is  the  lymphoid,  the 
solitary,  as  well  as  the  agminated  (Peyerian)  follicles  of  these 
parts  which,  like  other  lymphatic  glands,  are  especially  affected 
by  this  process.  More  accurate  histological  investigations  of 
this  metamorphosis  with  the  aid  of  modern  accessories  would 
be  in  place.  Tumefactions  of  the  follicles  show  themselves  con- 
jointly with  capillary  distentions  and  cell  proliferations.  Later, 
the  destruction  of  numerous  lymph-cells  takes  place  and  the 
finely  granular  so-called  tubercle  mass  is  formed.  This  softens 
and  occasions  the  formation  of  ulcers.  Usually,  the  lymphatic 
glands  of  the  mesentery  also  take  part  in  this  process. 

The  structural  conditions  of  the  follicles  in  abdominal  typhus 
are  very  similar  in  an  anatomical  point  of  view.  In  the  first 
or  catarrhal  period,  the  capillaries  of  the  Peyerian  follicles  are 
frequently  widened  to  a  considerable  degree.  Large  multinu- 
clear  lymph- corpuscles  are  met  with  here,  exactly  in  the  same 
manner  as  in  the  typhoid  metamorphosis  of  the  lymphatic 
glands  (p.  400).  By  means  of  several  injections  made  at  an 
earlier  period,  I  was  able  to  obtain  the  conviction,  at  least,  that 
in  this  stage  the  lymphatics  of  the  Peyerian  glands  are  still 
thoroughly  permeable.  Later,  with  the  destruction  of  the  cells, 
the  former  appear  to  become  stopped  up  and  impermeable.  It 
does  not  seem  to  be  in  place  here  to  speak  further  of  the  associ- 
ated processes  of  absorption,  of  the  softening  of  the  contents 
of  the  follicles,  and  of  the  formation  of  intestinal  ulcers  and 
sloughs.  The  latter  masses  consist  of  fine  granular  matter,  nu- 
clei, cells,  cell  remains,  etc.  The  associated  process  of  cicatri- 
zation takes  ,place  naturally,  by  a  new  formation  of  connective 
tissue.  Accurate  conclusions  are  not  easily  obtained  in  these 
cases,  as  I  know  from  my  own  experience,  so  that  a  careful  in- 
vestigation of  the  cases  at  hand  is  very  desirable. 

Finally,  with  regard  to  the  methods  of  preserving  microscopi- 
cal preparations  of  the  digestive  canal.  The  vertical  and  hori- 


DIGESTIVE    OEGANS.  451 

zontal  sections  may  be  preserved  moist,  with  or  without  pre- 
vious staining,  either  in  watery  or  more  concentrated  glycerine. 
If  they  have  been  carefully  washed  before  being  placed  in  the 
latter  fluid,  they  keep  well,  as  a  rule,  as  do  also  preparations 
of  their  vessels  and  lymphatics  injected  with  transparent  masses 
(carmine,  Prussian  blue).  According  to  previous  experience,  the 
nervous  and  ganglionic  plexuses  of  the  intestinal  canal  may  be 
best  preserved  by  freeing  them  from  the  residue  of  their  acid 
by  washing  in  distilled  water  some  time  before  mounting.  The 
method  of  depriving  tinged  preparations  of  their  water  by 
means  of  absolute  alcohol,  and  the  subsequent  mounting  in 
Canada  balsam  dissolved  in  chloroform,  must  be  designated  as 
very  serviceable  for  many  of  these  purposes.  Beautiful  and 
durable  review  preparations  for  low  powers  may  be  obtained  in 
this  way.  If  it  be  desired  to  mount  thicker  masses,  as,  for  in- 
stance, a  portion  of  intestinal  mucous  membrane  with  the  villi 
erect,  glass  cells  are  to  be  employed.  A  skilful  manipulator 
will  be  able  to  make  a  handsome  preparation  with  one,  even 
with  Canada  balsam. 

There  remains  for  us  to  consider,  finally,  the  intestinal  con- 
tents, and  the  faecal  masses  which  are  formed  from  the  latter. 
Although  these  are  not  often  objects  of  medical  examination,  and 
though  disgust  deters  many  observers  from  the  investigation  of 
the  latter  substances,  nevertheless,  in  consequence  of  the  multi- 
plicity of  their  elements,  they  are  both  very  instructive,  and  not 
always  easy  objects  of  microscopic  examination.  The  alimen- 
tary pulp  which  has  been  altered  by  the  saliva  and  the  gastric 
juice,  and  has  left  the  stomach,  has,  as  you  know,  received  the 
name  of  the  chyme.  In  its  further  progress  there  become 
mixed  with  it  the  secretions  of  the  liver,  of  the  pancreas,  and 
of  the  various  follicles  of  the  mucous  membranes,  as  well  as 
exfoliated  epithelium,  gland-cells,  and  the  mucous  corpuscles 
of  the  intestinal  canal ;  while  other  matters,  such  as  fat,  albu- 
minous bodies,  and  salts  are  removed  by  absorption  into  the 
lacteal  system.  The  chyme  naturally  presents  very  consider- 
able differences  according  to  the  nature  of  the  food ;  in  the  car- 
nivora  it  is  different  from  that  of  the  herbivora. 

We  omit  here  the  substances  which  are  dissolved  in  the  chyme. 


452 


SECTION    SEVENTEENTH. 


Its  elements  consist  of  molecules  and  drops  of  fat,  altered  mus- 
cular fibres,  portions  of  connective  tissue  (in  carnivorous  ani- 
mals fragments  of  cartilage  and  bone),  starch-granules,  various 
vegetable  tissues,  etc.  Fig.  244,  which  represents  the  contents 


Fig.  244.  Contents  of  the  small  intestine  of  a  rabbit. 

of  the  small  intestine  of  a  rabbit,  may  give  us  a  conception  of 
the  constitution  of  the  chyme  after  a  vegetable  diet.  In  the 
specimen  we  meet  with  starch-granules  in  various  stages  of  dis- 
solution, in  part  already  changed  into  empty  hollow  vesicles, 
epidermoidal  tissue,  prosenchyma  cells,  spiral  fibres,  etc. 

By  the  onward  movement  through  the  large  intestine,  the 
mass  undergoes  further  changes.  The  digestive  properties  of 
the  so-called  intestinal  juices  make  themselves  felt ;  the  lym- 
phatics absorb  the  fluid  portions,  and,  by  the  transformation  of 
the  biliary  pigment,  as  wrell  as  by  putrefactive  decomposition, 
the  masses  assume  the  color  and  smell  of  faeces. 

Numerous  elementary  particles  of  the  food,  such  as  filaments 
of  muscular  substance,  fat-tissue,  bundles  of  connective  tissue, 
elastic  fibres,  etc.,  are  still  to  be  met  with.  The  muscular 
fibres  are  frequently  separated  into  disks,  and  have  a  greenish 
tinge  from  the  biliary  pigment.  Numerous  remains  of  vege- 
table alimentary  matters,  starch  granules,  spiral  vessels,  epider- 
moidal tissue,  substances  which  we  have  already  mentioned  in 
speaking  of  the  contents  of  the  small  intestines,  show  themselves 
in  the  human  excrements.  Remarkable  fyecal  discharges  which 


DIGESTIVE    OEGANS.  453 

cause  great  solicitude  to  hypochondriacs,  and  may  also  astonish 
the  physician,  may  frequently  be  readily  demonstrated  by  the 
microscopical  examination  to  be  merely  remains  of  food. 

The  human  f seces  are  always  very  rich  in  fragments  and  fila- 
ments of  the  Leptothrix. 

With  the  name  of  meconium  has  been  designated  the  dark, 
pitch-like  stools  of  the  new-born  child.  They  contain  decom- 
posed bile,  separated  and  decaying  epithelium  and  cells  of  the 
intestinal  canal,  as  well  as  small  hairs  from  the  integument 
which  have  been  swallowed  with  the  amniotic  fluid.  The  me- 
conium is  rich  in  fats,  and  the  ethereal  extract  forms  a  deposit 
of  numerous  crystals  of  cholesterine. 

Numerous  alterations  in  consistence,  color,  and  constituents 
are  presented  by  the  f  secal  masses  in  disease.  The  most  remark- 
able stools  are  found  in  dysentery,  abdominal  typhus,  and  chol- 
era. The  alimentary  constituents  here  diminish  more  and  more, 
as  does  also,  as  a  rule,  the  decomposed  bile  ;  the  intestinal  secre- 
tions and  the  separated  cells,  on  the  contrary,  increase.  Albu- 
minous masses,  coagulated  fibrine,  and  blood  may  be  associated 
with  them. 

Dysenteric  stools  contain  desquamated  cylindrical  cells,  mu- 
cous and  pus  corpuscles,  cell  nuclei,  gland-cells,  fibrinous 
coagula,  blood-cells,  and  clots  of  blood. 

The  peculiar  evacuations  which  occur  in  abdominal  typhus,  at 
the  height  of  the  disease,  show,  together  with  epithelium,  gland- 
cells,  pus-corpuscles,  and  a  fine  granular  substance  with  nuclei, 
which  has  been  regarded  as  the  cast-off  ulcerative  products  of 
the  Peyerian  and  solitary  glands.  Not  unfrequently,  blood- cor- 
puscles also  occur  in  these  evacuations. 

We  mention,  finally,  the  cholera  stools.  The  rice-water-like 
dejections  in  this  disease  contain  very  large  numbers  of  mucous 
corpuscles,  but,  on  the  contrary,  only  very  little  cylindrical 
epithelium. 

Crystalline  deposits  of  the  ammonio-phosphate  of  magnesia 
(fig.  245)  are  found  in  the  alkaline  faeces  of  healthy  as  well  as  of 
diseased  persons.  They  present  a  rhomboidal  form,  and  most 
frequently  appear  as  three-sided  prisms  with  the  two  corners 
corresponding  to  one  side  blunted,  in  the  so-called  coffin-lid  form. 


454 


SECTION   SEVENTEENTH. 


In  consequence  of  the  general  diffusion  of  the  phosphatic 
salts  of  magnesia  in  the  solid  and  fluid  portions  of  the  organism, 

the  double  combination  we  are  at 
present  considering  forms  one  of 
the  most  frequent  occurrences  as 
a  result  of  the  development  of 
ammonia. 

Seldom,  on  the  contrary,  do  we 
Fig.  245.  crystals  of  the  ammonio-phos-     find  in  the   intestinal  canal  (but 

phate  of  magnesia. 

even  in   the    stomach,  however) 

crystalline  deposits  of  taurin,  a  conjugate  compound  of  one 
of  the  two  biliary  acids  (fig.  246).  Further  chemical  pro- 
cedures are  necessary,  as  a  rule,  for  the  recognition  of  this  body, 
as  well  as  of  cholesterine. 


Fig.  246.  Crystals  of  taurin.    a,  completed  six-sided  prisms ;  &,  indefinite  sheath-like  masses 
from  an  impure  solution. 

"We  cannot  leave  the  microscopical  analysis  of  the  faeces  with- 
out first  mentioning  certain  of  its  animal  parasites. 

A  large  infusory  animalcule,  covered  on  all  sides  with  cilia, 
the  Paramsecium  coli  of  Malmsten,  has  hitherto  had  no  practi- 
cal significance.  It  has  been  observed  a  few  times  in  the  large 
intestines  of  human  cadavers,  as  well  as  in  the  stools.  The  same 
is  also  true  of  the  Cercomonas  intestinalis,  a  small  creature  pro- 
vided with  a  whip -like  cilia,  discovered  by  Lambl.  It  has  been 
met  with  in  the  hyaline  intestinal  excretions  of  children,  in  in- 
testinal catarrhs,  as  well  as  in  typhoid  and  choleraic  diseases 


DIGESTIVE    OKGANS.  455 

(Davaine).  Quite  fresh  intestinal  evacuations,  or  such  as  have 
not  yet  become  cold,  should  be  used  for  their  investigation 
(Ekecrantz). 

The  microscopical  recognition  of  the  ova  of  the  most  familiar 
human  helminths  is,  on  the  contrary,  of  much  greater  practical 
importance  (Davaine,  Lambl,  Leuckart  and  others).  Leaving 
out  of  consideration  the  trichina,  the  embryos  of  which  creep 
out  in  the  maternal  body  and  then  perforate  the  intestinal  walls, 
the  ova  of  the  remaining  nematodes  do  not  become  developed  in 
the  human  body,  but  are  expelled  and  appear  in  the  stools ; 
likewise,  although  merely  casually,  those  of  the  tapeworms 
which  have  been  set  free  by  the  rupture  of  a  proglottis.  It  is 
easy  to  recognize  the  ova  of  the  parasites  dwelling  in  the  lower 
portion  of  the  intestine,  especially  of  the  Oxyuris  vermicularis, 
numbers  of  which  are  presented  by  every  microscopical  prepa- 
ration taken  from  the  external  surface  of  a  portion  of  faeces 
(Yix).  It  is  more  difficult,  on  the  contrary,  to  discover  the  ova 
of  the  nematodes  which  live  higher  up  in  the  intestinal  canal, 
such  as  the  Ascaris,  as  they  do  not  occur  in  the  mucus  which 
envelopes  the  solid  faecal  masses,  but  rather  in  the  interior  of 
the  latter. 

The  more  solid  masses  of  the  faeces  are  to  be  spread  out  with 
water  for  the  examination,  or  the  coating  of  slime  is  to  be  se- 
lected (with  Oxyuris).  The  mucous  coating  scraped  from  the 
intestinal  walls  with  a  spatula  also  presents  an  abundance  of 
this  helminth  (Vix). 

We  give  a  short  resume  of  the  characteristics  of  the  ova  of 
these  helminths  (fig.  247). 

Tricocephalus  dispar  (2).  Ova  double  contoured,  oval,  trun- 
cated at  both  poles,  shell  and  vitellus  of  a  brownish  color. 
Length,  0.0239-0.0257"' ;  breadth,  0.0111'". 

Ascaris  lumbricoides  (1).  Ova  roundish  or  oval,  measuring 
0.0363-0.03S6'",  next  to  the  largest  of  all.  The  shell  of  the 
ovum  has  a  double  contour  and  is  still  covered  by  the  transpar- 
ent, indentated  areole  of  an  albuminous  enveloping  substance. 

Oxyuris  vermicularis  (3).  Ova  mostly  transparent,  double 
contoured,  oval  shells  (frequently  having  an  asymetrical  curva- 
ture). Length,  0.0231-0.0248'";  width,  0.0102-0.0115'". 


456 


'SECTION"    SEVENTEENTH. 


Distoma  hepaticum  (4).  Eggs  oval,  very  large,  yellowish. 
Length,  0.0572-0.0616'" ;  breadth,  0.0332-0.0399'".  The  ante- 
rior pole  with  the  operculum  more  flattened.  Egg-shell  double, 
contents  .a  cell  aggregation  and  vitelline  spheres. 


Fig.  247.  Ova  of  the  most  familiar  helminths  of  man,  from  a  drawing  communicated  by  Prof. 
Leuckart  (all  magnified  870  diameters).  1.  Ascaris  lumbricoides.  2.  Tricocephalus  dispar.  3. 
Oxyuris  vermicularis.  4.  Distoma  hepaticum.  5.  D.  lanceolatum.  6.  Taenia  niediocanellata. 
7.  T.  solium.  b.  Bothriocephalus  latus. 

Distoma  lanceolatum  (5).  The  brown  double  shelled  oval 
eggs  are  much  smaller,  0.01T7-0.0199'"  long,  0.0133'"  broad, 
are  evacuated  at  a  later  period  than  the  previous  variety,  and 
contain  an  oval  embryo,  measuring  0.0115— 0.0133'",  with 
clusters  of  granules  in  the  posterior  parts  of  its  body. 

Bothriocephalus  latus  (8).  Eggs  oval,  averaging  0.03KX" 
in  length  and  0.0199'"  in  the  middle  transverse  diameter ;  they 
are  enveloped  by  a  simple,  hard,  brown  shell,  whose  anterior 
pole  constitutes  a  distinctly  interrupted,  hood-shaped  oper- 
culum. 

Tsenia  solium.  The  ova,  which  develop  within  the  so-called 
proglottides,  present  variations  in  accordance  with  their  age. 


DIGESTIVE    ORGANS.  457 

The  ovum  (7)  which  contains  an  embryo  sometimes  shows  an 
oval  enveloping  layer  of  albumen  and  a  globular,  thick,  mani- 
foldly contoured,  brownish  inner  shell  0.0133'"  in  diameter, 
the  surfaces  of  which  are  covered  with  closely  arranged  ciliae. 
This  contains  the  spherical  embryo,  which  measures  0.008'", 
and  is  provided  with  six  booklets.  Sometimes  the  outer  layer 
of  substance  (which  formed  the  original  vitelline  layer)  is 
wanting.  Undeveloped  ova  are  smaller,  globular,  at  first  with- 
out the  inner  envelope,  and  enclose  a  vitelline  sphere  and  a 
special  aggregation  of  embryonic  cells. 

Tsenia  mediocanellata.  Ova  (6)  quite  similar,  but  markedly 
oval  and  almost  regularly  provided  with  the  original  vitelline 
membrane.  The  size  and  other  characteristics  of  the  egg-shell 
the  same  as  in  the  previous  animal. 

Together  with  these,  the  presence  in  the  faeces  of  the 
familiar  hooks  of  the  Tsenia  and  their  younger  forms,  as  well 
as,  in  the  trichina  disease,  the  sexually  mature  examples  of 
these  worms,  is  applicable  for  the  diagnosis  of  a  helminthic 
disease. 


Section  <§igl)teentt)* 

THE  PANCREAS,  LIVER,  AND  SPLEEN. 

WE  have  still  remaining  the  two  large  glandular  organs 
connected  with  the  intestinal  canal,  the  pancreas  and  the  liver. 
The  spleen  is  also  to  be  discussed  here. 


Fig.  248.    Glandular  canals  of  the  rabbit's  pancreas,  after  Saviotti.    a  Larger  excretory  duct ; 
&  that  of  an  acinus ;  c  finest  capillary  ducts. 

We  can  despatch  the  pancreas  with  rapidity.  The  methods 
for  its  examination  are  the  same  as  are  ordinarily  used  for  the 
larger  racemose  glands.  The  fresh  organ,  the  usual  methods 
of  maceration,  portions  hardened  in  alcohol  or  chromic  acid 


THE   PANCREAS,    LIVER,    AND    SPLEEN.  459 

with  the  addition  of  the  reagents  customary  for  glands,  permit 
of  the  recognition  of  its  structure.  The  pancreas  of  the  small 
rodentia,  the  mouse,  rat,  and  rabbit,  spread  out  flat,  present 
handsome  appearances,  while  the  examination  of  the  human 
pancreas  is  very  generally  found  to  be  somewhat  difficult,  in 
consequence  of  the  abundance  of  fat  granules  in  the  gland 
cells.  Injections  of  the  blood-vessels  succeed  readily;  those 
of  the  gland-ducts  (fig.  248)  are  to  be  attempted  with  cold 
flowing  mixtures,  wTith  Briicke's  soluble  Prussian  blue,  for 
example.  The  syringe  may  suffice  for  this  purpose,  when 
carefully  directed.  The  constant  pressure  renders  better  service 
for  injecting  the  finest  capillary  passages  (c)  which  run  between 
the  gland-cells. 

The  liver,  on  the  contrary,  requires  a  more  accurate  discus- 
sion, in  consequence  of  its  numerous  peculiarities.  The  inves- 
tigation of  this,  the  most  voluminous  of  all  the  glands  of  the 
body,  is  in  fact  difficult,  so  that  some  of  its  structural  conditions 
still  remain  matters  of  controversy. 

Each  of  the  previously  mentioned  glandular  organs  shows 
the  observer  at  once,  together  with  the  paren- 
chyma cells,  an  investing  inembrana  propria 
(which,  it  is  true,  may  be  replaced  by  the  ad- 
jacent connective-tissue  layer).  While  now 
the  cells  of  the  liver  are  to  be  recognized 
with  the  greatest  facility,  the  question  as  to  the 
existence  of  the  membrana  propria  causes  the 
microscopist  great  embarrassment. 

The  most  simple  procedure  suffices  to  de- 
monstrate the  hepatic  cells  (fig.  249).  If  the 
fresh  organ  be  cut  into,  and  a  knife-blade  scrap- 
ed over  the  cut  surface,  the  brownish  mass, 
diluted  with  some  fluid,  presents  numerous  ex- 
amples, either  single,  in  series,  or  in  reticulated  fragments.  The 
adjacent  figure  shows  the  characteristic  form,  the  finely  granu- 
lar cell-contents,  very  generally  intermingled  with  isolated  fat- 
molecules  and  the  nucleus,  two  of  which  not  unfrequently  lie 
in  one  cell-body  (according  to  our  present  views,  a  proof  of  the 
cell-division).  A  special  cell-membrane  cannot,  however,  be 


460 


SECTION   EIGHTEENTH. 


demonstrated  on  the  cells  of  the  liver;  its  place  is  occupied 
much  more  by  a  somewhat  hardened  cortical  layer. 

The  so-called  hepatic  lobules  have  been  distinguished  for  a 
long  time.  These  islets  of  the  substance  of  the  tissue  are  some- 
times brownish  red  internally  with  a  brownish  periphery,  some- 
times the  colors  are  reversed.  In  most  mammalia  they  become 
blended  with  each  other  at  their  peripheries,  but  are,  neverthe- 
less, here  and  there  more  distinctly  demarcated. 

The  microscope  shows  as  a  cause  for  such  a  sharp  division 
of  the  hepatic  lobules  a  strongly  developed  connective-tissue 
boundary  layer.  The  liver  of  the  cat,  the  sheep,  and  more 
especially  that  of  the  pig,  is  of  this  variety.  Many  things  which 
are  only  to  be  recognized  with  difficulty  in  the  organ  of  other 
animals  and  of  man,  appear  more  distinctly  in  the  last-mention- 
ed animal.  The  pig's  liver  has,  therefore,  very  properly  been 


Fig.  250.  Transverse  section  of  a  human  hepatic  lobule. 

recommended  by  modern  histologists  as  an  extremely  suitable 
object  for  examination. 

With  the  aid  of  a  sharp  scalpel  a  fine  transverse  section  may 
be  obtained  from  such  a  lobule  of  the  quite  fresh  organ,  just 
beneath  the  surface,  for  instance.  Valentine's  double-knife 
(p.  Ill)  has  been  recommended  by  others  for  this  purpose.  It 
is  much  better,  as  we  shall  have  to  mention  hereafter,  to  make 


THE    PANCREAS,    LIVER,    AND    SPLEEN.  461 

use  of  livers  hardened  in  alcohol  or  chromic  acid  for  the  pre- 
paration of  such  specimens.  We  also  recommend  the  freezing 
method. 

Such  a  transverse  section  (fig.  250)  shows  the  columns  of  the 
liver-cells  or  the  cell-network  arranged  in  a  general  radiated 
manner,  and,  at  the  same  time,  these  columns  of  cells  united 
together  in  a  reticular  manner  by  short  transverse  rows.  In 
human  and  mammalian  livers  the  cells  of  such  a  network  usu- 
ally lie  in  single  rows,  and  are  only  double  in  places  at  the  nodal 
points;  nevertheless,  many  variations  occur.  A  system  of 
similar  spaces  appears  in  such  preparations,  for  the  most  part 
with  great  distinctness. 

If  for  the  purpose  of  further  investigations  the  blood-vessels 
be  filled  with  transparent  substances  (either  as  a  single  injection 
by  the  vena  hepatica  or  the  portal  vein,  or  wVh  two  masses  by 
the  two  veins  simultaneously),  the  radially  arranged  capillary 
network  appears  with  surprising  beauty,  and  one  is  at  the  same 


Fig.  251.  The  injected  liver  of  the  rabbit  with  the  branches  of  the  portal  and  hepatic  veins. 

time  convinced  that  the  origin  of  the  above-mentioned  spaces, 
which  were  shown  by  the  transverse  section  of  the  hepatic 
lobule,  is  due  to  the  capillaries  of  the  vascular  network,  and 
likewise  that  the  rounded  central  space  (fig.  251)  is  the  trans- 
verse section  of  a  branch  of  the  hepatic  vein  (vena  intralobula- 
ris  of  Kiernan). 


462  SECTION    EIGHTEENTH. 

Fig.  251  may  represent  to  the  reader  the  finer  arrangement 
of  the  blood-vessels.  Several  lobules  appear  to  be  supplied  by 
each  branch  of  the  portal  vein  with  finer  ramifications,  run- 
ning in  a  lateral  direction,  which  are  confined  to  the  interve- 
ning spaces  between  the  lobules  (venae  interlobulares),  and  in 
the  centre  are  noticed  the  branches  of  the  hepatic  nervous  sys- 
tem. A  few  branches  of  the  hepatic  artery  also  enter  the  cap- 
illary network  at  its  peripheral  portion,  so  that  the  injection 
may  be  practised  by  the  latter  vessel  with  the  same  success  as 
by  the  portal  veins. 

Even  in  the  fresh  condition,  the  previously-injected  liver 
shows  the  capillary  network  occupied  by  the  columns  of  the 
hepatic  cells,  so  that  two  kinds  of  network,  that  of  the  blood- 
vessels and  that  of  the  cellular  trabeculse,  are  actually  thrust 
into  each  other. 

In  well-hardened  organs,  however,  where  the  razor  affords 
very  fine  sections,  these  investigations  may  be  made  in  a  much 
finer  manner.  Simple  alcohol  may  be  employed,  and  likewise 
Clarke's  mixture  of  alcohol  and  acetic  acid  (p.  141). 

Beale  especially  recommends  the  use  of  alcohol  to  which  a 
few  drops  of  a  solution  of  soda  has  been  added  (p.  142).  Such 
preparations,  freed  from  adherent  matters  by  working,  and 
tinged  with  carmine  or  (which  is  likewise  to  be  highly  recom- 
mended) hsematoxylin,  afford  exactly  the  appearance  as  if  the 
cells  were  embedded  quite  free  in  the  spaces  of  the  capillary 
network. 

This  view  was,  in  fact,  maintained  for  a  long  time,  although 
the  contrary  opinion  might  also  have  been  defended  with  the 
same  propriety,  namely :  that  a  cellular  network,  enclosed  in  a 
homogeneous  membrane,  was  permeated  by  the  reticulated  la- 
cunar  system  of  capillary  blood-currents. 

The  modern  accessories  have  led  us  a  considerable  step 
further  in  this  matter. 

Fine  sections  from  a  liver  hardened  to  the  consistence  suit- 
able for  brushing  (I  generally  employ  alcohol  for  this  purpose, 
at  first  with  considerable  water,  then  with  less)  permit  of  the 
removal  of  the  liver-cells,  although  only  over  more  limited 
spaces  (fig.  252).  In  this  way  there  is  left  a  fine  and  extremely 


THE   PANCREAS,    LIVER,    AND    SPLEEN. 


463 


delicate  network  (a)  formed  of  a  homogeneous  membrane  which 
separates  the  blood-current  from  the  cell  columns.  If  carmine 
tiiigeing  be  resorted  to,  the  columns  of  hepatic  cells  which 
were  not  removed  by  the  brushing  will  appear  very  beauti- 
fully; then,  however,  one  will  also  recognize  in  this  hyaline 


Fig.  252.    Framework  substance  from  the  liver  of  the  rabbit,    a,  homogeneous  membrane  with 
nuclei ;  6,  thread-like  strip  of  the  latter  ;  c,  several  hepatic  cells  not  removed  by  the  brushing. 

membrane  of  the  reticular  framework,  together  with  the  cap- 
illary nuclei,  a  few  small  and  more  rounded  nuclei  which  are, 
in  adult  creatures,  for  the  most  part  shrunken. 

If  the  liver  of  a  new-born  child,  of  a  human  embryo  of  the 
later  months,  or  of  a  mammalial  animal  of  a  corresponding 
period  of  life  be  used,  the  fine  hyaline  membrane  alluded  to 
appears  in  places  with  great  distinctness  as  a  double  membrane, 
one  of  the  layers  of  which  corresponds  to  the  capillary  walls, 
while  the  other  limits  the  cellular  network. 

According  to  this,  there  is  no  longer  any  doubt  that  a  thin, 
often  indeed  extremely  fine  layer  of  homogeneous  connective 
tissue  supporting  substance  (in  continuity  with  the  connective 
tissue  which  envelops  the  hepatic  lobules),  condensed  more  like 
a  membrane  towards  the  cellular  network,  constitutes  or  replaces 
the  long-sought  membrana  propria  of  the  hepatic  cell  columns. 
To  it  belong  as  a  system  of  connective-tissue*  corpuscles,  those 
nuclei  which  occur  more  abundantly  in  the  earlier  periods  of 
life,  and  are  often  surrounded  by  a  distinct  cell-body. 

While  these  two  membranes,  the  connective-tissue  frame- 
work substance  and  the  membrane  of  the  capillary-vessels,  ap- 
pear at  first  separated,  in  older  creatures  they  often  make  the 


464  SECTION    EIGHTEENTH. 

erroneous  impression  as  if  they  were  blended  (see  below).  The 
beautiful  results  which  Remak  made  known  years  ago  concerning 
the  manner  of  formation  of  the  liver  may,  therefore,  be  con- 
firmed on  the  organ  of  the  new-born  and  the  adult.  "We  are 
indebted  in  part  to  Beale,  but  especially,  however,  to  E.  Wag- 
ner, for  a  knowledge  of  the  facts  to  which  allusion  has  been 
made. 

"We  come  now  to  the  discussion  of  the  biliary  ducts.  Their 
branches,  provided  with  a  fibrous  membrane  and  a  covering  of 
shorter  cylindrical  epithelium  cells,  surround  the  lobules,  in 
parts  more  continuous,  as  an  extremely  delicate  circular  net- 
work (cat,  rabbit,  Guinea-pig),  in  part  in  the  form  of  separated, 
sinuous,  ramified  passages ;  thereby  maintaining  a  course  sim- 
illar  to  that  of  the  branches  of  the  portal  vein.  "With  careful 
injections  of  the  ductus  hepaticus,  these  passages  (the  muscular 
tissue  of  which,  as  Heidenhain  has  shown,  is  rendered  apparent 
by  treatment  with  chloride  of  palladium,  1 :  900)  may  be  recog- 
nized with  tolerable  facility ;  likewise,  after  having  once  observed 
these  canals  on  fine  sections  of  the  hardened  organ,  with  the 
assistance  of  brushing  and  staining.  Here  and  there,  the  latter 
procedure  will  also,  occasionally,  show  still  finer  passages  which 
run  towards  the  interior  of  the  lobule. 

The  aid  of  finer  injections  of  the  biliary  passages  is  naturally 
necessary  for  the  further  examination  of  their  structure,  and  the 
relation  of  the  ultimate  biliary  ducts  to  the  cell-columns  is  to  be 
decided  by  them.  In  consequence  of  the  extreme  delicacy  of 
the  structure  of  the  lobules,  and  the  impediment  which  the  bile 
accumulated  in  these  canals  presents  to  the  injecting  fluid,  this 
procedure  is  difficult,  and  is  also,  as  a  rule,  especially  with 
solutions  of  gelatine,  thwarted  by  rapidly  appearing  extrava- 
sations. 

It  is  only  recently  that  success  has  been  obtained  in  arriving 
at  a  decided  result  (Budge,  Andrejevic,  MacGillavry,  Frey, 
Hering,  Eberth) ;  namely,  in  injecting  a  fine  and  extremely 
elegant  biliary  network  which  permeates  the  entire  hepatic 
lobule  and  surrounds  the  individual  hepatic  cells  with  its 
meshes.  An  analogous  condition  has  since  been  discovered  in 
the  racemose  glands  (p.  413). 


THE    PANCREAS,    LIVER,    AND    SPLEEN. 


465 


For  this  purpose  use  the  quite  fresh  liver  of  an  animal  which 
has  just  been  killed,  and  either  the  apparatus  for  constant 
pressure  described  at  page  189  and  represented  in  fig.  77,  or 
that  of  Ilering.  A  previous  removal  of  the  bile  is  unnecessary. 
An  aqueous  solution  of  Prussian  blue  (p.  186,  note)  serves  as  an 
injection  fluid  which  is  capable  of  filling  the  marvellous  net- 
work of  a  lobule  by  a  very  moderate  pressure  (20-25  mm.  of 


Fig.  253.  Biliary  capillaries  of  the  rabbit's  liver.  1.  A  part  of  a  lobule,  a,  vena  hepatica  ;  6, 
branch  of  the  portal  vein  ;  c,  biliary  ducts ;  d.  capillaries ;  e,  biliary  capillaries.  2.  The  biliary 
capillaries  (ft)  in  their  relation  to  the  capillary  blood-vessels  (a).  3.  The  relation  of  the  biliary 
capillaries  to  the  hepatic  cells,  o,  capillaries ;  6,  hepatic  cells ;  c,  biliary  ducts ;  d,  capillary 
blood-vessels. 

mercury) ;  in  other  cases  only  by  a  cautious  increase  of  the 
pressure  (40-45  mm.).  A  rounded  network  of  extremely  nar- 
row cylindrical  tubes,  measuring  only  0.001-O.OOOS'",  will  then 
be  seen  to  permeate  the  entire  hepatic  lobule.  Interwoven 
with  the  capillary  network  of  the  blood-vessels,  it  at  the  same 
time  surrounds  the  gland-cells  with  its  individual  meshes,  so 
that  a  portion  of  the  surface  of  each  hepatic  cell  comes  into 
intimate  contact  with  these  finest  passages,  which  have  been 
appropriately  named  "  biliary  capillaries  "  (MacGillavry).  Our 
wood-cut,  fig.  253,  affords  the  reader  a  primary  representation 
of  this  structure  ;  1  shows  the  arrangement  in  the  lobule  with 
a  low  power,  2  shows  the  biliary  capillaries  and  the  capillary 
blood-vessels,  and  3  these,  together  with  the  hepatic  cells,  more 

'strongly  magnified. 
30 


466  SECTION    EIGHTEENTH. 

The  recognition  of  this  delicate  condition  was  at  first  success- 
ful only  in  a  few  varieties  of  the  mammalial  animals.  The 
injection  succeeds  with  tolerable  facility  in  the  rabbit ;  it  is 
more  difficult  in  the  dog,  the  cat,  the  hedgehog,  the  calf,  and 
the  Guinea-pig.  Essentially  the  same  structure  was  afterwards 
noticed  in  the  remaining  classes  of  the  vertebrate  animals 
(Hyrtl,  Ilering,  Eberth).  The  injection  of  indigo  carmine  in 
the  vein  of  the  living  animal  (comp.  p.  188),  which,  according 
to  the  statements  of  Chrczonszczewsky  and  Eberth,  is  likewise 
capable  of  bringing  out  the  network  of  the  biliary  capillaries,  is 
also  to  be  recommended  for  such  studies.*  What  is,  however, 
the  more  accurate  relation  of  the  biliary  capillaries  to  the  cells 
and  blood-vessels  of  the  liver  ? 

The  coluber  natrix  (fig.  254,  1)  shows,  in  the  most  elegant 
manner,  the  transversely-divided,  finest  biliary  passages  (c)  sur- 
rounded by  a  wreath  of  gland-cells  (b)  and  separated  by  these 
from  the  capillary  vessels  (a).  A  similar  arrangement  is  also 
presented  by  the  liver  of  the  salamander  (2). 

In  the  mammalia,  on  the  contrary,  the  fine  system  of  biliary 
passages  assumes  the  reticular  arrangement  represented  in  fig. 
253,  in  consequence  of  the  extensive  development  of  the  lateral 
branches.  Here,  now  (fig.  254,  3),  we  see  the  surface  of  each 
hepatic  cell  (&)  coming  in  contact  one  or  more  times  with  the 
biliary  capillaries  (c).  The  biliary  capillaries  and  capillary 
vessels  (a)  are,  however,  never  contiguous  to  each  other,  but, 
rather,  a  gland-cell  or  a  portion  of  one  always  separates  the  bili- 
ary from  the  blood  current.  Even  in  the  mammalial  animal, 
therefore,  notwithstanding  all  complications,  the  old  fundamen- 
tal plan  is  retained. 

If  the  injection  with  constant  pressure  has  succeeded — the 
process  should  be  discontinued  as  soon  as  a  few  lobules  on  the 
surface  of  the  liver  become  slightly  blue — the  organ  may  be 

*  Asp  showed  how  the  finest  biliary  passages  may  be  rendered  visible,  filled 
with  their  natural  contents.  He  injected  into  the  ductus  chelodocus  of  a  liv- 
ing animal  15  grammes  of  a  saturated  solution  of  gum  or  tallow.  Several 
days  later  the  creature  was  killed  and  the  liver  hardened  in  absolute  alcohol, 
chromic  acid,  or  bichromate  of  potash.  The  biliary  capillaries  then  appeared 
as  fine  gold-yellow  shining  filaments. 


THE    PANCREAS,    LIVER,    AND    SPLEEN. 


467 


examined  fresh.  It  is  more  suitable  to  afterwards  fill  the  blood- 
vessels with  strongly-acidulated  gelatine  and  carmine,  and  when 
the  liver  has  cooled,  to  cut  it  in  pieces  and  harden  it  in  strong 


Fig.  254.  The  finest  biliary  passages  of  the  liver :  1.  of  the  coluber  natrix  (after  Hering) ;  2.  of 
the  salamander  (after  Eberth) ;  3.  of  the  rabbit,  a,  blood-vessels ;  &,  hepatic  cells ;  c,  biliary 
capillaries. 

alcohol  to  which  a  few  drops  of  acetic  acid  has  been  added.  If 
a  weak  tingeing  with  carmine  be  subsequently  employed,  the 
preparations  obtained  are  very  handsome  and  instructive. 

If  the  injection  be  continued  too  long,  or  if  too  strong  a  pres- 
sure is  used,  there  follows,  according  to  MacGillavry,  an  extra- 


468  SECTION    EIGHTEENTH. 

vasation  into  the  lymphatic  vessels,  into  the  extremely-developed 
lymphatic  network  of  the  lobules.  It  is  believed,  at  the  first 
glance,  that  the  capillary  blood-vessels  have  been  filled,  so  de- 
ceptive is  the  appearance ;  more  accurate  investigation  shows 
that  the  injection  mass  surrounds  the  blood-vessel  like  a  mantel. 
The  investing  lymph-current  (which  reminds  one  of  a  similar 
condition  of  the  central  nervous  system,  p.  357),  therefore, 
occupies  the  space  intervening  between  the  capillary  walls  and 
the  connective  tissue  which  surrounds  the  trabecular  cell  net- 
work after  the  manner  of  a  membrana  propria. 

Such  extravasations  into  the  lymphatic  system,  which  finally 
lead  to  the  filling  of  the  interlobular  lymphatic  passages,  read- 
ily occur,  and  have  been,  here  and  there,  erroneously  accepted 
by  earlier  experimentalists  for  successful  injections  of  the  bili- 
ary passages. 

The  larger  lymphatic  canals  may  be  recognized  in  the  vicin- 
ity of  the  lobules.  They  are  regularly  arranged  and  have  a 
partly  isolated  course,  and  are  partly  united  into  networks  of 
unequal  size.  Even  here  these  lymphatics  begin  to  encircle,  in 
a  reticular  manner,  the  blood-vessels  and  biliary  canals  lying 
between  the  lobules,  which  is  always  the  case  with  the  larger 
branches  of  the  latter  vessels.  Furthermore,  according  to 
Teichmann's  statements,  the  human  liver  has  a  single  layered 
network  of  superficial  passages,  contained  in  the  peritoneal 
covering.  The  meshes  are  of  different  sizes  and  vary  in  diam- 
eter ;  they  are  now  and  then  enlarged  into  considerable  lymph- 
receptacles. 

The  nerves  of  the  liver  come  from  the  plexus  coeliacus  and 
consist  in  part  of  medullated,  in  part  of  Remak's  fibres.  They 
have  been  seen  to  pass  to  the  vessels,  the  biliary  ducts,  and  the 
covering  of  the  organ.  Osmic  acid  has  been  recommended  for 
their  more  accurate  examination. 

The  examination  of  the  hepatic  secretion  of  the  fresh  normal 
bile  shows  the  niicroscopist  a  clear  colorless  fluid  without  gran- 
ules or  drops  of  fat,  at  the  most  with  a  few  separated  cylindri- 
cal cells  tinged  with  coloring  matter.  The  cellular  elements  of 
the  hepatic  substance  proper,  in  contradistinction  to  many  other 
glands,  is  entirely  wanting  in  the  secretion,  so  that  we  still  find 


THE    PANCREAS,    LIVEE,    AND    SPLEEN. 


469 


ourselves  in  the  dark  with  regard  to  their  destiny  and  duration 
of  life. 

Under  more  abnormal  conditions,  sediments  are  formed  in 
the  contents  of  the  gall-bladder.  The  microscope  may  show 
slimy  masses,  with  larger  quantities  of  separated  cylindrical 
epithelium  and  granulated  spherical  cells  (mucous  and  pus  cor- 
puscles). In  bile  which  has  been  long  retained  in  the  gall- 
bladder one  meets  only  very  rarely  with  crystals  of  cholesteriue 
(comp.  p.  360) ;  occasionally,  on  the  contrary,  one  sees  deposits 
of  the  red  biliary  coloring  matter  or  bilirubin  (cholepyrrhin, 
biliphsein,  bilifulvin).  These  have,  for  the  most  part,  amor- 
phous structures,  and  appear  as  sausage-shaped,  bulbous  masses. 

By  treatment  with  chloroform,  larger  and  more  perfect  crys- 
tals, rhomboidal  prisms,  needles,  and  lamina  are  obtained.  The 
use  of  sulphuret  of  carbon  is  still  more  advisable.  Our  fig. 
253  shows  magnificent  crystals  of  bilirubin,  which  were  ob- 
tained in  the  latter  manner  by  Staedeler 
from  human  gall-stones.  It  has  not  as 
yet  been  definitely  decided  whether  bili- 
rubin and  hsematoidin  are  similar  or  only 
nearly  related  bodies. 

Pathological  changes  of  the  hepatic 
tissue  are  frequently  met  with.  Our 
knowledge  of  them  has  recently  been  es- 
pecially promoted  by  a  classical  work  of 
Frerichs,  and  the  interesting  investiga- 
tions of  E.  Wagner.  Here,  as  in  other 
glandular  organs,  we  find  the  cells  capable 
of  increase  and  of  manifold  changes,  but 
rarely  of  a  transformation  into  new  tissue 
elements ;  while  here  also  the  new  formations  may  proceed,  for 
the  most  part,  from  the  small  cell-like  structures  of  the  connec- 
tive-tissue framework. 

In  hypertrophy  of  the  liver  we  see  an  enlargement  of  the 
existing  gland-cells ;  so  that  they  have  gained  twice  and  even 
three  times  their  normal  circumference,  and  frequently  enclose 
two  and  sometimes  three  nuclei'.  In  other  cases  the  microscope- 
shows  small,  rounded,  pale  cells,  with  a  large  nucleus.  These 


Fig.  255.  Crystals  of  bilirnbin. 
1    from   sulphuret  of 


470  SECTION   EIGHTEENTH. 

young  formations,  which  have  proceeded  from  the  normal  hepa- 
tic cells,  may  constitute  the  greater  portion  of  the  parenchyma 
of  the  liver,  but  may  also  be  met  with  in  smaller  numbers,  to- 
gether with  the  large  cells  mentioned. 

A  few  brown  molecules  of  biliary  pigment  are  met  with  in 
the  hepatic  cells  of  healthy  persons.  In  obstructed  biliary  ex- 
cretion the  number  of  these  molecules  increases  (especially  in 
the  cells  adjacent  to  the  hepatic  vein),  or  the  cell  body  becomes 
yellow.  The  nucleus  may  also  become  tinged,  and  solid, 
rounded,  bulbous  or  rod-shaped  masses  of  a  yellow,  brownish-red 
or  greenish  color  appear  in  the  cell  contents.  Where  the  disease 
has  continued  for  a  longer  period,  concretions  of  the  biliary  pig- 
ment, frequently  in  the  form  of  rod-shaped  structures,  fill  the 
distended  biliary  capillaries  (O.  Wyss). 

The  deposition  of  fat  molecules  and  drops  of  fat  in  the  hepa- 
tic cells  has  already  been  mentioned  above.     Higher  degrees 
of    this   process   constitute   very   frequent 
physiological,  as  well  as  pathological  occur- 
rences  (fig.   256).      A  fatty  or    otherwise 
luxurious    diet,    combined   with    deficient 
bodily  exercise,  frequently  produces  such  a 
Fig.  256.  ceiis  of  the  fatty    condition,   a   so-called   fatty  liver.      It   is 

liver.  * 

thus  found  in  the  cadavers  of  quite  healthy 
individuals  who  have  perished  suddenly,  as  well  as  in  nurslings. 
If  cod-liver  oil  be  added  to  the  food  of  a  dog,  the  hepatic  cells 
of  the  animal  will  be  filled  to  a  considerable  degree  with  drops 
of  fat,  even  after  a  few  days,  and  after  eight  days  they  will  be 
quite  overloaded  with  the  same.  If  the  cod-liver  oil  be  with- 
held, this  superfluous  fat  will,  after  a  time,  disappear  entirely 
from  the  cells.  The  stuffing  process  produces  in  geese  such  a 
fatty  liver,  which  is  highly  esteemed  by  gourmands.  The  same 
condition  is  observed  in  other  cases  of  a  morbid  nature,  as,  with 
especial  frequency,  in  pulmonary  phthisis  and  dyscrasia  potato- 
rum.  Locally  circumscribed  overcharging  of  the  liver  with 
fat  also  frequently  occurs. 

If  we  follow  the  increasing  infiltration  of  the  liver-cells  with 
the  microscope,  we  see  the,  at  first,  small  drops  of  the  mole- 
cules of  fat  become  more  and  more  numerous  (a  £),  then  flow 


THE   PANCREAS,    LIVER,    AND    SPLEEN.  471 

together  into  a  few  drops  (c) ;  finally  these  also  unite  into  a 
single  drop  (d). 

If  such  fatty  livers  be  hardened  in  chromic  acid,  and  the  fine 
sections  be  rendered  transparent  with  alkalies,  the  deposition 
of  the  fat  will  be  found  to  proceed  in  an  interesting  manner 
through  the  cells  of  the  lobule. 

Introduced  by  the  portal  vein,  the  fat  is  first  deposited  in  the 
cells  which  belong  to  this  capillary  district,  that  is,  in  the 
peripheral  portion  of  the  hepatic  lobule.  The  process  then 
advances  step  by  step  in  a  central  direction,  so  that  soon  only 
the  central  cellular  trabeculse,  which  are  adjacent  to  the 
hepatic  vein,  remain  free  from  fat ;  finally,  the  deposition  of 
fat  also  takes  place  in  the  latter. 

Such  a  fatty  liver  will  indeed  astonish  us  by  the  slight 
quantity  of  blood  which  it  contains,  and  will  accomplish  less 
for  the  secretion  of  bile  than  the  normal  organ ;  but  its  cells 
(reminding  us  of  those  of  fat-tissue)  tolerate  this  fatty  deposit 
well,  on  the  whole,  and  frequently  resume  their  former  con- 
dition. 

It  is  otherwise,  on  the  contrary,  with  the  actually  fatty 
degenerated  liver.  Here,  as  indeed  everywhere,  the  structure 
is  destroyed  by  the  process  of  degeneration.  Such  a  meta- 
morphosis is  found,  for  the  most  part,  only  in  limited  portions 
of  the  hepatic  tissue,  in  the  vicinity  of  inflammatory  foci  and 
tumors. 

In  a  very  remarkable,  and  in  its  exciting  causes  still  com- 
pletely enigmatical  disease,  the  acute  or  yellow  atrophy  of  the 
liver,  there  is  observed  a  quick,  and  often  very  rapid  destruc- 
tion of  the  hepatic  cells,  so  that  in  their  place,  in  cases  of  a 
high  degree,  only  a  detritus  is  found,  consisting  of  partly  color- 
less, partly  brownish  granules,  fat-molecules,  and  drops  of  fat, 
as  well  as  crystalline  products  of  decomposition  (leucin  and 
tyrosin),  which  are  then  partially  removed  by  the  urine.  The 
framework  of  the  cellular  trabeculae  persists,  however,  so  that 
it  may  be  readily  isolated  with  the  brush ;  the  same  is  also  true 
of  the  capillary  walls.  If,  however,  the  attempt  be  made  to 
inject  the  latter,  numerous  extravasations  soon  take  place, 
obviously  because  now,  in  the  place  of  the  former  cells,  the 


472 


SECTION    EIGHTEENTH. 


softened  substance  of  the  capillary  walls  no  longer  affords  any 
support. 

We  have  just  alluded  to  the  crystalline  products  of  decom- 
position, the  occurrence  of  immense  quantities  of  which  in  the 
so-called  yellow  atrophy  was  first  observed  by  Frerichs. 

In  infectious  diseases,  in  typhoid,  so-called  pysemic  and 
septic  affections,  as  well  as  in  cases  of  malignant  intermittent 
fevers,  matters  occur  in  the  liver,  as  evidences  of  an  altered 
assimilation,  which  in  the  normal  organ  are  either  entirely 
wanting,  or  are  only  present  in  very  much  smaller  quantity. 
Among  these  are  to  be  enumerated  a  series  of  crystalline  sub- 
stances which  are  attributable  to  organic  bases. 


Fig.  257.     Crystalline  forms  of  tyrosin. 

Among  these,  tyrosin  and  leucin  stand  in  the  first  line. 
Tyrosin  (fig.  257)  appears  in  white  needles  of  a  silk-like  lustre, 
which  occur  in  part  more  isolated  (a),  in  part,  however,  united 
into  delicate  smaller  and  larger  groups  (b  1)).  Its  reactions 
may  be  ascertained  from  a  text-book  on  zoochemistry. 

Leucin  is  seen  in  various  forms  in  the  examination  of  the  hu- 
man body.  Among  these  are  frequently  seen  peculiar  druses 


THE    PANCREAS,    LIVER,    AND    SPLEEJST. 


473 


of  characteristic  appearance,  partly  small  spheres  (#),  partly 
semispherical  structures  (5),  partly  aggregations  of  such  masses 
(c  c£),  whereby  not  unfrequently  numerous  small,  flattened  seg- 


Fig.  268.    Various  crystalline  masses  of  leucin. 

ments  of  spheres  rest  upon  a  larger  spherical  body  (e  f).  Stra- 
tified spheres  (g  g]  with  smooth  borders  remind  one  of  starch 
granules;  others  have  a  rough  surface.  Quite  similar  druses 
of  fine  crystalline  needles  likewise  occur. 

Hypoxanthine  (or  sarciiie),  a  third  variety  of  these  products 
of  decomposition,  has  been  much  more  rarely  met  with  in  the 
diseased  liver.  With  regard  to  their  further  properties,  we 
must  again  refer  to  the  text-books  on  chemistry.  Their  com- 
binations with  nitric  and  muriatic  acids  produce  characteristic 
crystalline  forms.  Our  fig.  259  shows,  in  its  upper  half,  the 
appearance  of  the  nitric  acid  salt,  while  the  lower  portion  af- 
fords a  representation  of  the  muriatic  salt.  The  smaller,  cu- 
cumber-shaped crystals  of  the  nitrate  of  hypoxanthine  are  of  a 
particularly  characteristic  nature. 

There  is  still  another  nearly  related  body,  xanthine,  which 
constitutes  an  element  of  the  urine,  and  is  also  met  with  in 
various  organs ;  it  occurs  in  the  healthy  and  diseased  liver,  and 
may  here  be  casually  mentioned.  Fig.  260  shows  the  crystal- 
line forms  of  the  combinations  with  nitric  and  muriatic  acids. 


474 


SECTION   EIGHTEENTH. 


The  upper  half  represents  the  nitrate  of  xanthine ;  the  lower 
portion  of  the  figure  is  occupied  by  the  characteristic  crystals 
of  the  nitrates. 


Fig.  259.  Crystals  of  the  nitrate  and  muriate  of  hypoxanthine. 


Fig.  260.  Crystals  of  nitrate  and  muriate 
of  xanthine. 


Fig.  261.  Crystals  of  cystine. 


Cystine  (fig.  261),  a  product  of  the  decomposition  of  the 
body,  characterized  by  the  large  proportion  of  sulphur  which  it 
contains,  has  also  been  observed  crystallized  in  colorless,  six- 


THE    PANCKEAS,    LIVER,    AND    SPLEEN.  475 

sided  laminse  or  prisms  in  the  products  of  decomposition  of  the 
liver,  in  the  above-mentioned  infectious  diseases.  It  likewise 
occurs  in  the  normal  organ. 

While  the  above-mentioned  pathological  processes  show  a 
transformation  of  the  hepatic  cells,  in  many  other  diseased  con- 
ditions of  the  organ  the  latter  either  remain  entirely  unaffected, 
or  are  changed  in  a  secondary  manner,  and  then  only  subse- 
quently, as,  for  instance,  by  compression. 

In  rnaiiy  cases  of  malignant  intermittent  fever  an  extensive 
development  of  melanine  has  been  observed  in  the  tissue  of  the 
spleen.  Pigmented  cells  and  flake-like  bodies,  the  latter  fre- 
quently of  considerable  size,  pass  through  the  \ena  lienalis  into 
the  blood  of  the  portal  vein,  and  from  here  into  the  vascular 
district  of  the  liver.  If  the  brown,  island-like  figures'  of  the 
lobules,  which  are  often  visible  to  the  naked  eye,  be  examined 
it  will  be  seen  that  the  capillary  vessels,  and  also  larger  branches 
which  belong  to  the  portal  and  hepatic  veins,  are  obstructed  by 
these  piginented  masses.  Similar  emboli  are  also  met  with  in 
other  organs,  especially  the  kidney  and  the  brain.  Whether 
the  cerebral  symptoms  which  have  been  observed  in  such  dis- 
eases are  to  be  thereby  explained  still  remains  uncertain. 

The  so-called  waxy,  lardaceous,  or  amyloid  degeneration  of 
the  liver,  which,  equally  and  together  with  that  of  the  spleen 
and  kidney,  is  not  a  rare  occurrence,  does  not  affect  the  hepatic 
cells  alone.  We  have  already  mentioned  this  process  cursorily 
at  the  vascular  system  (p.  390).  The  nature  of  the  homoge- 
neous, dull  glistening,  peculiarly  reacting  substance  was  for  a 
long  time  a  subject  of  controversy,  and  a  definite  conclusion 
has  not  been  arrived  at  even  at  the  present  time.  We  are  now 
aware,  at  least,  that  all  the  above  names  are  wrong,  inasmuch 
as  a  product  of  the  metamorphosis  of  albuminous  matters  is 
present,  but  not  fatty  substances,  or  even  amylon  and  cellulose 
(Kekulc,  C.  Schmidt).  The  microscopic  examination  has  shown 
that  the  walls  of  the  small  arterial  branches  and  of  the  hepatic 
capillaries  undergo  this  metamorphosis.  The  walls  of  the  ves- 
sels affected  become  thickened,  stiff,  homogeneous,  and  glisten- 
ing ;  thereby  a  decrease,  occasionally  an  occlusion  of  the  lumen 
takes  place,  so  that  a  colorless  cylinder  results.  The  normal, 


476  SECTION   EIGHTEENTH. 

fine  granular  contents  of  the  cell  itself  disappear  more  and 
more,  to  make  place  for  a  homogeneous  substance,  and  the  nu- 
cleus is  gradually  destroyed.  The  cells,  which  are  transformed 
into  flakes,  sometimes  hang  firmly  together  in  the  form  of  con- 
sistent, irregular-shaped  lamellae. 

We  have  already  mentioned  above  (p.  136)  the  peculiar  re- 
action of  iodine  and  sulphuric  acid  on  the  substance  in  ques- 
tion. We  will  here  discuss  this  more  thoroughly  by  way  of 
example. 

The  section,  which  has  been  made  from  the  fresh  hepatic  tis- 
sue and  washed  out,  is  to  be  placed  in  a  weak  aqueous  solution 
of  iodine  ;  it  is  well  to  continue  the  immersion  for  some  time, 
and,  to  facilitate  the  saturation,  the  preparation  should  be 
turned  'over  a  few  times.  Even  now  a  characteristic  reddish- 
brown  is  noticed.  The  greater  portion  of  this  fluid  should  then 
be  removed  and  a  covering-glass  placed  over  the  preparation ; 
concentrated  sulphuric  acid  should  then  be  allowed  to  flow  in 
from  the  side  as  slowly  as  possible.  At  very  unequal  periods, 
either  immediately  or  after  several  minutes  or  hours,  or  even 
later,  there  is  either  an  increase  of  the  red  color  or  a  dirty  violet, 
more  rarely  a  blue  color  produced.  Another  procedure  is, 
however,  more  advantageous.  Fine  sections  from  preparations 
hardened  in  alcohol  are  to  be  placed  in  a  glass  box  with  distilled 
water  and  10-20  drops  of  tincture  of  iodine  added.  Then,  gen- 
erally after  five  minutes  (when  the  coloring  of  the  amyloid  sub- 
stance usually  takes  place),  the  preparation  is  to  be  washed  and 
again  placed  in  clean  water  and  3-6  drops  of  concentrated  sul- 
phuric acid  added.  The  characteristic  tinge  is  obtained  some- 
times rapidly,  sometimes  only  after  2-3  hours,  when  the  ex- 
examination  is  to  be  made  with  the  addition  of  glycerine. 
Such  objects  may  be  preserved  for  a  sometimes  shorter,  some- 
times longer  period ;  but  not,  however,  according  to  previous 
experience,  in  the  form  of  permanent  cabinet  preparations. 

In  tubercle  of  the  liver  the  ordinary  elements  are  first  recog- 
nized ;  nuclei,  small  cells  in  the  condition  of  shrinking,  to- 
gether with  these,  large,  flake-like  structures  with  several  nuclei. 
It  was  formerly  considered  that  these  substances  originated  in 
the  interstitial  connective  tissue.  At  the  present  time,  the  vas- 


THE    PANCREAS,    LIVER,    AND    SPLEEN.  477 

cular  ramifications  are  considered  to  be  the  points  of  origin  of 
the  tubercles. 

A  hypertrophy  of  the  connective-tissue  framework  substance 
which  permeates  the  liver,  with  a  corresponding  transformation 
of  the  compressed  lobules  and  gland-cells,  is  found  in  the  so- 
called  granulated  liver,  cirrhosis  hepatis.  The  examination  may 
be  made  in  various  ways.  Sections  from  the  fresh  tissue  may  be 
picked  and  treated  with  reagents,  or,  which  we  would  prefer, 
suitably  hardened  objects  may  be  used.  At  the  commence- 
ment of  the  process  it  is  noticed  that  the  scanty  connective 
tissue  which  separates  the  hepatic  lobules  proliferates  consider- 
ably; its  cells  increase  and  the  interstitial  substance  becomes 
transformed  into  a  firm,  fibrillated  substance  reminding  one  of 
cicatricial  tissue.  This,  by  its  further  increase,  compresses  the 
hepatic  lobules  more  and  more,  so  that  gradually  only  island- 
like  remains  of  the  same,  with  shrivelled,  brownish  cells,  are  to 
be  met  with.  These  are  in  part  tinged  with  hsematine ;  they 
contain  in  part  yellow  corpuscles  or  fatty  substances,  or  finally, 
amyloid.  The  membrana  propria  may  hereby  be  still  recog- 
nizable, but  is  likewise  finally  transformed  into  connective 
tissue.  The  groups  and  aggregations  of  brownish  molecules 
which  are  found  embedded  in  the  connective  tissue  proceed 
from  the  remains  of  disintegrated  hepatic  cells.  The  capilla- 
ries likewise  gradually  atrophy,  and  in  the  same  proportion  that 
the  gland-substance  disappears,  while  the  interacinous  biliary 
passages  often  remain  permeable  for  a  long  time.  Injections 
rarely  succeed. 

In  carcinoma  of  the  liver  the  connective-tissue  framework 
of  the  organ  is  very  probably  transformed  immediately  into  the 
framework  or^stroma  of  the  carcinoma.  The  origin  of  the  car- 
cinoma cells  remains  obscure. 

We  have  finally  to  discuss  the  spleen.  This  organ,  which 
still  presents  so  much  that  is  enigmatical  concerning  its  physi- 
ology, was  also,  until  within  a  few  years,  only  imperfectly  un- 
derstood with  regard  to  its  structure,  and,  in  fact,  numerous 
accessories  are  requisite  if  we  would  obtain  a  knowledge  which 
is  in  any  degree  satisfactory  concerning  the  latter.  The 
extreme  softness,  the  excessive  vascularity  of  the  spleen,  and 


478  SECTION   EIGHTEENTH. 

the  numerous  elastic  septal  formations  render  the  manipulation 
very  difficult.  The  latter  system  of  septa  (and  herein  a  close 
parallel  with  the  related  lymphatic  glands  of  the  creature  is 
shown)  is,  in  large  mammalial  animals,  highly  developed  and 
presents  a  complicated  framework,  while  in  small  creatures  it 
diminishes  more  and  more,  even  to  an  almost  complete  disap- 
pearance. The  spleens  of  the  smaller  rodents  (rabbit,  Guinea- 
pig,  squirrel,  etc.)  form  therefore,  like  the  lymphatic  glands  of 
these  creatures,  the  most  suitable  objects  for  the  primary  inves- 
tigation. 

One  would  be  very  much  deceived  if  one  were  to  expect  to 
find  in  the  fresh  spleen,  even  with  the  most  careful  preparation, 
more  than  isolated  elements,  blood-cells,  contractile  lymph-cor- 
puscles, vascular  epithelium,  etc.  In.  consequence  of  the  great 
softness  of  the  organ,  there  is  scarcely  an  appearance  of  even 
fragments  of  the  delicate  but  developed  connective-tissue 
framework  which  permeates  the  whole  gland.  Injections  are 
also  frequently  frustrated  by  the  extreme  softness  of  even  the 
freshest  spleen.  We  are  here,  therefore,  admonished  to  use 
hardening  accessories,  and,  as  the  drying  methods  are  not  to  be 
thought  of,  to  employ  alcohol,  chromic  acid,  and  the  bichro- 
mate of  potash. 

Assuming  that  we  wish  to  prepare  in  this  manner  the  spleen 
of  a  small  mammalial  animal  (rabbit,  Guinea-pig),  the  whole 
organ  may  be  immersed.  With  the  spleens  of  larger  creatures 
it  is  judicious  to  expose  only  a  portion  to  the  influence  of  the 
above  reagents,  and  to  previously  force  a  stream  of  the  fluid 
through  the  blood-vessels  with  a  syringe. 

For  many  purposes  alcohol  is  quite  sufficient,  especially  if  it 
is  used  diluted  at  first,  and  then,  after  a  few  days,  replaced  by 
alcohol  which  is  stronger.  After  6-8  days  (occasionally,  how- 
ever, only  after  a  few  weeks)  the  spleen  is  in  a  condition  suit- 
able for  making  sections,  and  has  also  gained  such  a  consistence 
that  it  may  be  conveniently  brushed.  Increased  hardening  no 
longer  permits  of  the  latter  important  procedure,  or  only  very 
imperfectly ;  and,  as  a  rule,  nothing  further  can  be  done  with 
such  spleens.  Frequently  a  spleen  is  only  rendered  fit  for  in- 
jecting after  an  immersion  for  24-28  hours  in  ordinary  prepa- 


THE    PANCREAS,    LIVER,    AND    SPLEEN.  479 

ration  alcohol.  Injected  spleens  (and  here  again  only  transpa- 
rent, partly  solidifying,  partly  cold-flowing  masses  should  be 
used)  are  also,  as  a  rule,  to  be  hardened  in  alcohol. 

For  many  textural  conditions,  however,  chromic  acid  renders 
decidedly  better  service  than  alcohol.  Portions  not  too  large 
should  be  placed  in  an  ample  quantity  of  the  fluid,  and  at  first 
a  weak  solution  of  the  acid,  0.2-0.1  per  cent.,  is  to  be  used. 
This  is,  after  several  days,  to  be  exchanged  for  one  of  twice  the 
strength,  and  afterwards  perhaps  for  one  that  is  still  more  con- 
centrated. If  test  sections  be  made  from  time  to  time  with  the 
razor  and  the  brush,  good  objects  will  be  obtained. 

I  have  seen  the  finest  results,  however,  from  the  use  of  the 
chromate  of  potash.  If  a  solution  of  about  1  per  cent,  be  com- 
menced with,  and  the  concentration  slightly  increased  daily, 
after  several  days  a  period  arrives  when  the  organ,  which  is  not 
yet  sufficiently  hardened,  must  be  still  further  hardened  by 
means  of  alcohol.  After  a  few  days  further  the  entire  tissue 
has,  with  great  preservation,  gained  the  proper  condition. 

The  method  of  further  investigation  consists  in  the  preparation 
of  thin  sections  in  various  directions,  which  are  to  be  examined 
partly  unbrushed,  partly  freed  from  blood-  and  lymph-corpuscles 
by  means  of  the  brush.  An  immersion  for  several  hours  in 
pure  glycerine  is  useful,  and  tingeing  with  carmine  is  of  the 
same  importance  as  for  the  lymphatic  organs.  The  system  of 
septa  likewise  comes  out  very  beautifully  in  this  way.  Acids, 
the  reagents  customary  for  the  demonstration  of  smooth  muscu- 
lar fibres,  such  as  chloride  of  palladium  and  the  double  staining 
with  carmine  and  picric  acid,  serve  for  the  recognition  of  its 
finer  texture. 

Nevertheless,  although  the  directions  given  lead  to  the  harden- 
ing of  fresh,  moderately  consistent  mammalial  spleens,  do  not 
think  that  every  human  organ  can  be  thereby  mastered.  The 
maceration  which  we  meet  with  in  our  post-mortems,  the  often 
considerable  softening  which  may  be  found  in  diseased  bodies, 
not  unfrequently  render  the  suitable  hardening  of  the  spleen 
a  difficult  piece  of  work,  for  the  termination  of  which,  not  only 
days,  but  also  weeks  and  months  are  necessary.  Here  the 
weak,  watery  alcohol  is  soon  to  be  replaced  by  that  which 


480  SECTION    EIGHTEENTH. 

is  stronger;  finally,  operate  with  absolute  alcohol.  Billroth 
recommends  the  action  of  chromic  acid  in  very  concentrated 
solution  (even  to  20  per  cent.)  on  small  portions  of  spleen,  for 
hardening  in  typhoid  affections  of  the  organ.  The  framework 
and  the  relative  arrangement,  it  is  true,  become  visible  in  fine 
sections  in  this  way ;  the  cell  metamorphoses  and  other  delicate 
textural  conditions  must  be  followed  sooner  on  the  fresh  organ 

o 

or  on  a  portion  which  is  but  slightly  hardened,  for  a  chromic 
acid  of  such  strength  produces  great  shrinking. 

Preparations  of  the  spleen  are  to  be  mounted  partly  in  the 
ordinary  moist  way  in  glycerine,  partly  dry,  whereby,  however, 
absolute  alcohol  and  Canada  balsam  dissolved  in  chloroform 
should  always  be  used.  Sections  from  transparent  injections, 
somewhat  strongly  tinged  with  carmine,  afford  by  the  latter 
method  very  handsome  preparations  for  examination.  The 
system  of  trabeculae  also  appears  finest  by  such  treatment. 

If  now  we  inquire  what  information  as  to  the  structure  of 


Fi£.  262.    Transverse  section  of  a  rabbit's  spleen,    a,  Malpighian  corpuscles ;  Z>,  the  reticular 
framework  of  the  pulp,  with  the  spaces  filled  by  the  venous  blood-current. 

the  spleen  has  been  obtained  by  the  aid  of  these  accessories, 
the  answer  may  be  given  that  our  organ  constitutes  a  com- 
plicated lymphatic  gland,  in  which  the  lymph-current  is  re- 


THE   PANCREAS,    LIVER,    AND    SPLEEN.  481 

placed  by  a  blood-current,  and  is  therefore  a  blood-lymph 
gland,  as  we  might  express  ourselves  in  brief. 

The  Malpighian  corpuscles  of  the  spleen  (fig.  262  a)  show 
the  structure  of  the  lymphatic-gland  follicles,  and,  in  so  far  as 
they  do  not  pass  over  into  tubes  or  the  tissue  of  the  pulp,  they 
have  likewise  on  their  surface  a  more  narrow-meshed,  reticular 
border.  Nuclei  occur  in  a  portion  of  the  nodal  points,  espe- 
cially in  younger  animals.  The  capillary  system  presents 
nothing  remarkable,  and,  with  suitable  objects,  brushing  usually 
succeeds  with  facility.  We  would  recommend  the  spleen  of 
the  sheep  as  being  very  suitable. 

In  many  small  creatures  (rodentia,  for  example,  the  rabbit, 
Guinea-pig,  and  marmot)  there  is  also,  at  some  distance  from 
the  periphery,  a  narrow-meshed,  concentric  layer  of  reticular 
connective  tissue,  the  significance  of  which  requires,  however, 
further  elucidation. 

The  pulp  (fig.  262  5)  consists  of  a  system  of  tubes  arising 
from  the  Malpighian  bodies  and  united  together  in  a  reticular 


Tig.  263.  From  the  pulp  of  the  human  spleen,  brushed  preparation  (combination),  a,  pulp 
tube  with  the  delicate  reticular  framework ;  6,  transverse  section  of  the  cavernous  venous  canal ; 
c,  longitudinal  section  of  such  a  one ;  d}  capillary  vessel  in  a  pulp  tube,  dividing  up  at  e ;  /, 
epithelium  of  the  venous  canal ;  g,  side  view  of  the  same ;  A,  its  transverse  section. 

manner,  which  present  a  much  finer  and  narrower-meshed 
reticular  framework  (fig.  263  a)   and  which  is  much  more 

difficult  to  isolate.     We  are  indebted  to  Billroth  for  its  recoff- 
31 


482  SECTION    EIGHTEENTH. 

nition.  Permeated  by  capillaries,  it  encloses  in  a  sometimes 
more  reticular,  sometimes  variable  form  a  system  of  passages 
which  serve  for  the  reception  of  the  venous  blood — a  discovery 
to  which  I  was  led  in  the  year  1860  by  the  injection  of  the  human 
spleen,  and  which  was  afterwards  also  confirmed  by  Billroth. 
This  system  of  venous  passages  reminds  one  essentially  of  the 
cavernous  canals  which  permeate  the  cortical  substance  of 
the  larger  lymphatic  canals  and  serve  for  the  removal  of  the 
lymph. 

These  passages  of  the  spleen  pulp  (c)  are,  however,  without  a 
membranously  thickened  wall,  inasmuch  as  the  same  fine  reti- 
cular tissue  which  occurs  within  the  pulp-tubes  also  encloses 
the  venous  current.  The  passage  is  also  lined  by  an  unstratified 
epithelium  (/),  which  in  man  'has  a  peculiar  spindle  shape,  and 
the  rounded  nuclei  of  which  project  into  the  lumen. 

The  spaces  of  the  spleen  are,  as  the  first  examination  shows, 
filled  with  lymph-cells.  As  the  walls  of  the  fine  veins  do  not 
appear  to  be  membranously  thickened,  a  wandering  of  these 
cells  into  the  venous  current,  and,  with  a  more  considerable  in- 
crease of  the  current,  a  forcible  penetration  of  blood-cells  into 
the  pulp-tubes,  is  conceivable.  "We  therefore  see  the  colored 
blood-corpuscles  in  part  unchanged,  in  part  in  various  stages  of 
ruin,  and,  by  no  means  rarely,  free  in  the  tissue  of  these  pas- 
sages. 

Peculiar  flake-like  structures  containing  blood-corpuscles  and 
reminding  one  of  cells  were  described,  even  many  years  ago,  as 
being  found  in  the  spleen  (Kolliker,  Ecker,  Gerlach,  and 
others).  The  localities  of  their  occurrence  as  well  as  their 
genesis  require  renewed  investigations,  although  there  is  cer- 
tainly here  an  admission  of  an  amoeboid  cell. 

With  regard  to  the  course  of  the  blood-vessels,  it  may  be  said 
that  the  greater  portion  of  the  arterial  trunks  can  be  readily 
followed  in  injected  preparations  ;  likewise  the  division  of  the 
venous  branches.  It  is  also  easy  to  perceive  how  the  capillary 
vessels  of  the  Malpighian  corpuscles  are  formed  by  the  breaking 
np  of  the  former.  A  single  or  double  arterial  branch  is  gene- 
rally met  with  on  and  in  the  Malpighian  corpuscle ;  veins  do 
not  occur  here. 


THE   PANCREAS,    LIVER,    AND    SPLEEN.  4&3 

The  recognition  of  the  capillary  blood-vessels  in  the  spleen- 
pulp  as  well  as  their  connection  with  the  venous  passages  is,  on 
the  contrary,  extremely  difficult,  and  even  to  the  present  time 
there  is  no  agreement  of  opinions  concerning  this  important 
structural  question.  Many  investigators  assume,  after  the  ex- 
ample of  Gray  (whose  fine  monograph  is  still  too  little  known 
in  Germany),  a  direct  continuation  of  moderately  large  capil- 
laries into  the  venous  canals ;  others 
believe  that  they  have  convinced 
themselves  that  a  very  close  net- 
work of  extremely  fine  capillary 
tubes  occur  here  (Key,  Stieda). 
According  to  our  own  observations 
(and  we  find  ourselves  in  harmony 
with  the  most  thorough  monograph- 
ist  of  the  organ,  with  TV.  Miiller), 
the  passage  of  the  arterial  splenic 
blood  into  the  venous  roots  takes  ,  Fi£-  ^4-  *™?  the  sheeP'8 

(double  injection),     a.  reticular  fraine- 

place,  on  the  contrary,  in  man  and     work  of  the  PuiP  ;&,  intermediate  puip- 

current;   c,   its    continuation  into  the 

the  mammalia  by  wall-less  currents.     ^Sbra^iT"1  incomplete  wajls;  * 
These  pass  through  the   reticular 

framework  of  the  pulp-tubes  by  using  the  interstices  of  the 
fibres  and  lymph-cells,  we  might  say,  somewhat  as  the  water  of 
a  failing  brook  takes  its  course  between  the  pebbles  of  the  bed. 
Our  fig.  263  shows  a  capillary  vessel  d  which  at  e  is  distributed 
into  the  network  of  the  pulp,  and  may  represent  to  the  reader 
the  commencement  of  the  intermediate  pulp-current.  The 
blood  or  the  injection  mass  then  passes  from  the  spleen  pulp 
through  the  spaces  of  the  limiting  layer  (c)  into  the  commence- 
ment of  the  veins.  Fig.  264  will  render  this  continuation 
(b  c)  intelligible,  and  at  the  same  time  show  that  a  reticular,  scale- 
like  coagulation  of  the  injection  mass  over  the  lymph-cells  of  the 
pulp-tube  explains  the  pretended  capillaries  of  Key  and  Stieda. 
For  the  recognition  of  these  important  conditions  we  recom- 
mend the  injection  of  a  sheep's  spleen,  as  cautiously  as  possible, 
but  also  as  completely  as  possible,  with  a  very  intense  blue 
gelatine  mass,  and  to  tinge  the  sections  made  from  the  hardened 
organ  with  carmine.  The  comparison  with  the  natural  injec- 


484  SECTION   EIGHTEENTH. 

tion  is  of  high  value  as  a  control.  The  organ,  hardened  in  a 
solution  of  chromate  of  potash  (1  per  cent.)  and  afterwards 
in  alcohol,  shows  us,  in  fine  sections  treated  with  glycerine,  the 
uninjured  blood-corpuscles  in  the  same  places  in  which  we  have 
met  with  the  blue  injection  fluid  (W.  Miiller). 

Lymphatics  are,  as  a  rule,  very  readily  recognized  in  the  cap- 
sules of  large  mammalial  animals  (ox,  pig,  sheep).  Their  in- 
jection almost  never  leads  into  the  interior  of  the  organ,  and, 
with  the  puncturing  method,  the  reticular  venous  canals  are 
regularly  filled.  The  opinion  seems  justifiable,  therefore,  that 
lymphatics  are  wanting  in  the  tissue  of  the  spleen  (Teichmann, 
Billroth,  Frey).  Subsequently,  however,  Tomsa  succeeded  in 
injecting  lymphatic  vessels  in  the  system  of  septa  of  our  organ. 

The  trabecular  framework  of  the  human  spleen  (which  arises 
from  the  capsule  and  divides  the  organ  into  innumerable  irregu- 
lar compartments)  consists  of  connective  tissue,  elastic  fibres, 
and  scanty  muscular  elements.  It  requires  the  same  methods 
of  investigation  as  the  equivalent  structures  of  the  lymphatic 
glands  (comp.  p.  394). 

For  the  study  of  the  splenic  nerves  the  fresh,  thoroughly 
washed-out  spleen  is  to  be  treated  with  alkalies  and  acetic  acid ; 
organs  immersed  in  pyroligneous  or  chromic  acid  are  also  to  be 
used. 

It  is  known  that  the  spleen  frequently  participates  in  the 
more  general  processes  of  disease.  In  certain  infectious  dis- 
eases, as  in  intermittent  and  typhoid,  its  swellings  present  char- 
acteristic occurrences.  Attention  has  more  recently  been  paid 
to  a  surcharging  of  the  blood  with  colorless  cells,  induced  by 
enlargement  of  the  spleen  and  lymphatic  glands.  This  condi- 
tion, leucsemia,  we  have  already  mentioned  at  the  blood  (p. 
232).  These  metamorphoses  of  the  organ,  as  well  as  its  various 
degenerations  and  new  formations,  are  known  in  their  coarser 
relations,  but  not,  however,  or  only  very  incompletely,  in  their 
finer  texture.  In  a  case  of  this  affection  of  a  high  degree  I 
once  met  with  a  considerable  hypertrophy  of  the  pulp  and  an 
astonishing  development  of  the  capillary  system  lying  in  the 
pulp-tubes. 

Several  years  ago  Billroth,  an  observer  who  has  accomplished 


THE    PANCREAS,    LIVEK,    AND    SPLEEN.  485 

very  much  for  the  knowledge  of  the  spleen,  made  an  inroad 
into  this  domain  by  the  aid  of  the  improved  methods. 

The  finer  changes  of  the  spleen  in  abdominal  typhus  are  still 
very  imperfectly  known.  The  more  or  less  swollen  organ  does 
not  show,  in  injected  preparations,  the  remarkable  distention  of 
the  veins  and  capillaries  which  we  have  mentioned  above  as 
occurring  under  the  same  conditions  in  the  lymphatic  glands 
and  Peyerian  follicles  (comp.  p.  401  and  395) ;  still,  there  are 
certainly  slight  dilatations  of  the  vessels. 

Of  interest  is,  on  the  contrary,  the  occurrence  in  abdominal 
typhus  of  the  large  multinuclear  cells  in  the  venous  spaces,  the 
same  as  we  have  formerly  mentioned  as  occurring  in  the  pas- 
sages of  the  lymphatic  glands.  Here,  also,  in  the  later  periods, 
the  characteristic  molecular  ruin  of  these  cell-masses  takes 
place,  in  so  far  as  they  are  not  previously  removed  from  the 
spleen  by  the  blood-current. 

The  numerous  granules  which  are  met  with  in  our  organ  in 
miliary  tuberculosis  are,  as  a  rule,  located  in  the  tissue  of  the 
pulp  and  only  rarely  in  the  Malpighian  corpuscles.  Their 
contents  is  the  familiar  fine  granular  substance  with  shrivelled 
nuclei  and  cells. 

In  the  so-called  hemorrhagic  infarctions  of  the  spleen,  which, 
as  is  known,  are  not  rare  occurrences,  the  microscopic  analysis 
shows  in  the  overloaded  venous  passages  the  appearance  and 
the  phases  of  metamorphosis  of  masses  of  coagulated  blood. 

In  the  ordinary  hypertrophy,  the  reticular  tissue  of  the  pulp 
may  present  great  thickening,  so  that  sometimes  it  appears  sim- 
ilar to  that  of  the  Malpighian  corpuscles.  In  conditions  of 
high  degree  the  lymphatic  cells  of  the  latter  disappear;  in 
their  places  fine  granular  substance  and  yellowish  pigment  are 
noticed. 

In  cases  of  malignant  intermittent  those  pigmentated  flakes 
and  pigment-cells  are  produced,  which,  passing  out  through  the 
vena  lienalis,  may  give  rise  to  embolia  of  frequently  considera- 
ble size,  first  in  the  liver  and  then  in  other  organs,  such  as  the 
kidneys,  brain,  etc.  (comp.  p.  233). 

We  have  already,  at  the  liver,  mentioned  the  amyloid  degen- 
eration of  the  tissue  of  the  spleen  which  occurs  so  frequently 


486  SECTION    EIGHTEENTH. 

The  organ,  which  has  become  more  firm,  readily  permits 
of  hardening  in  alcohol,  whereby  (as  was  casually  remarked  at 
the  liver)  the  capability  of  reacting  of  the  amyloid  substance  is 
not  lost,  and  fine  sections  permit  of  the  recognition  of  the  de- 
posits in  a  convenient  manner.  In  many  cases  we  notice  the 
Malpighian  corpuscles  first  attacked  ;  in  other  cases  the  parietal 
layer  of  the  venous  canals  in  the  pulp  has  undergone  amyloid 
degeneration. 

The  first  form  of  deposit,  known  to  the  pathological  anato- 
mists under  the  name  of  the  "  sago  spleen,"  shows  the  arterial 
walls  to  be  the  point  of  origin. 

In  the  other,  more  rarely  occurring  variety,  the  lardaceous 
spleen,  on  the  contrary,  the  transverse  sections  of  the  venous 
passages  of  the  pulp  are  surrounded  by  a  thicker,  homogeneous 
amyloid  layer. 

Attempts  at  preserving  such  preparations  of  pathologically 
metamorphosed  spleens  must  be  made  according  to  the  direc- 
tions given  for  the  normal  tissue. 


Section  jNituteentl). 

RESPIRATORY  ORGANS. 

THE  investigation  of  the  respiratory  apparatus  presents  rela- 
tively less  difficulties  to  the  microscopist  than  that  of  the  organs 
described  in  the  previous  section. 

The  larynx,  trachea,  and  bronchi  consist  of  tissues  which  have 
already  been  described  by  us  in  previous  chapters,  so  that  the 
methods  there  given  are  to  be  repeated  here. 

The  epithelium  of  the  parts  mentioned,  coverings  of  epithe- 
lial cells,  with  the  exception  of  the  stratified  epithelium  on  the 
lower  (true)  vocal  cords,  are  examined  either  by  scraping  them 
off  in  the  fresh  condition  or  after  being  hardened  in  alcohol  on 
thin  stained  sections.  The  latter  method  also  serves  for  the 
recognition  of  the  texture  of  the  mucous  membrane  and  the 
racemose  glands  which  occur  here.  The  latter  not  unf  requently 
become  changed  in  consequence  of  catarrhal  processes,  their 
vesicles  become  enlarged,  and  their  cell-contents  changed.  The 
'  cartilages  may  be  examined  either  fresh  or  after  being  hardened. 
Calcifications  and  ossifications  of  the  same,  which,  as  is  known, 
are  frequent  occurrences  in  after  life,  are  to  be  examined  fresh 
or  after  having  been  decalcified  by  chromic  acid.  The  distri- 
butions of  the  nerves  are  to  be  studied  in  acetic  or  pyroligneous 
acid  preparations  ;  lymphatic  vessels  are  to  be  injected  by  the 
puncturing  method  from  the  submucous  tissue. 

The  same  methods  of  treatment  serve  for  the  larynx,  trachea, 
and  bronchi ;  their  smooth  muscular  elements  require  the  so- 
frequently  mentioned  accessory  which  is  used  for  the  demon- 
stration of  that  tissue. 

The  investigation  of  the  lungs  is,  however,  quite  different. 
Portions  of  the  fresh  tissue  when  picked  readily  show  the  elas- 
tic fibres  and  membranes,  especially  after  the  application  of 


488  SECTION    NINETEENTH. 

acetic  acid  or  alkalies.  The  epithelial  structures  of  the  alveoli 
and  the  finest  bronchial  ramifications  may  also  be  recognized. 
But  in  general  the  results  are  limited  to  these,  and  such  exam- 
inations are  not  unfrequently  considerably  impeded  by  the 
numerous  air-bubbles  in  the  preparation. 

Other  methods  of  treatment  are  therefore  necessary. 

These  consist  of  drying,  or  the  use  of  the  same  hardening 
solutions  which  we  have  already  so  frequently  mentioned.  If 
possible,  the  blood-vessels  should  always  be  previously  injected, 
and  for  many  investigations  it  is  almost  indispensable  to  have 
the  respiratory  canals  distended. 

The  whole  lung,  or  portions  of  the  same,  when  carefully 
dried,  assume  a  consistence  which  permits  of  sections  being 
conveniently  made  in  all  directions.  These  when  softened  per- 
mit of  the  satisfactory  recognition  of  the  greater  portion  of 
their  details,  and  the  application  of  staining  methods,  of  acetic 
acid  and  alkalies,  constitute  further  advantageous  accessories. 
It  is  preferable  to  moderately  inflate  the  lung  which  is  to  be 
dried  bv  the  bronchus  or  the  air-passages,  and  after  tying  these,  to 

t/  JL  &  t/  O 

hang  it  in  the  sun  or  near  a  stove  to  harden.  The  injection  of 
the  air-passages  (from  which  the  air  may  be  previously  removed 
by  means  of  an  air-pump)  with  uncolored  (also  colored)  gelatine 
5s  a  very  good  method.  Injections  of  the  blood-vessels  with 
transparent  colors  and  a  menstruum  which  solidifies,  such  as 
gelatine,  permit  of  the  same  treatment.  Sections  made  from 
these  and  softened  present  beautiful  appearances,  especially  if 
the  injection  fluid  was  not  too  watery.  With  smaller  creatures 
the  injection  should  be  made  by  the  arteria  and  vena  pulmo- 
nalis ;  with  those  which  are  larger,  generally  only  by  single 
branches  of  each  of  these  vessels.  The  injection  is  in  general 
to  be  regarded  as  an  easy  one,  even  with  small  mammalia,  if 
the  syringe  is  only  very  cautiously  managed. 

If  the  finer  textural  relations  are  to  be  examined,  alcohol, 
chromic  acid,  and  chromate  of  potash  are  to  be  used  for  the  im- 
mersion of  portions  of  the  uninflated  lung  or  the  whole  organ, 
whereby  it  is  also  well  to  inject  the  bronchi  with  the  hardening 
fluid.  The  employment  of  these  fluids  also  forms  the  chief 
means  for  the  recognition  of  pathological  structural  changes. 


KESPIRATOBY    OEGANS. 


489 


Still  better,  even  here,  is  the  preparatory  inflation  of  a  whole 
organ,  or  the  injection  of  its  air-passages  with  uncolored  gelatine, 
the  blood-vessels  having  been  previously  filled  with  cold-flowing 
transparent  mixtures.  If  such  a  lung  be  suspended  by  the 
trachea,  in  a  large  vessel  filled  with  alcohol,  it  affords,  after 
several  days,  excellent  views  of  its  entire  structure ;  and  if  it 
was  fresh  when  exposed  to  this  preparatory  treatment,  even  the 
alveolar  epithelium,  that  cellular  covering  which  was  so  exten- 
sively disputed  years  ago,  and  which  is  nevertheless  so  easy  to 
recognize,  may  be  seen. 

The  ultimate  terminal  ramifications  of  the  bronchial  passages 
pass  over  into  a  system  of  acute-angled  ramified  canals,  which  pre- 
sent thin,  sinuous  walls.  These  (fig.  265  c)  are  beset  laterally  as 
well  as  terminally  by  groups  of  the  alveoli  or  lung-vesicles,  the  so- 
called  infundibula  (a),  while  other 
alveoli  (b)  constitute  the  sinuosities 
mentioned  on  the  walls  of  these 
passages  (F.  E.  Schulze).  The  in- 
f  imdibulum  corresponds  to  the  pri- 
mary lobule  of  a  racemose  gland, 
.and  may  be  seen  in  sections  of  lungs 
which  are  simply  dried,  or  in  those 
of  which  the  air-passages  have  been 
filled  with  transparent  materials. 
Another  way  of  obtaining  a  view 
of  them  is  by  the  corrosion  method. 
The  air-passages  are  to  be  injected 
with  a  colored  resinous  mass,  and 
then  the  lung-tissue  destroyed  by 
the  long-continued  action  of  con- 
centrated muriatic  acid.  The  relation  of  the  pulmonary  lobule 
to  its  bronchial  tube  is,  however,  not  easy  to  recognize. 

For  the  closer  examination  of  the  air-vesicles  and  their  more 
minute  construction,  fine  sections  of  the  tissue  which  has  been 
hardened  in  fluids  are  used. 

For  this  purpose  an  entirely  fresh  lung,  which  has  been  care- 
fully isolated  and  injected,  is  selected  ;  it  should  be  immersed 
in  alcohol  to  harden,  and  the  sections  when  ma'de  are  to  be  care- 


rig.  265.  Two  so-called  infnndibula  of 
the  lungs  (a),  with  the  finest  bronchial 
twigs  (c),  and  the  pulmonary  vesicles  (6). 


490 


SECTION   NINETEENTH. 


fully  colored  in  the  familiar  mixture  of  equal  parts  of  the  am- 
moniacal  solution  of  carmine  and  glycerine  (p.  152),  and  finally 
washed  out  in  water  containing  a  little  acetic  acid.  To  pro- 
ceed with  more  certainty,  the  sections  may  be  taken  from  the 
surface  of  the  organ,  as  recommended  by  Eberth.  In  this 
way  one  obtains  a  great  number  of  surface  and  profile  views 
of  the  alveoli,  and  is  protected  from  mistaking  them  for  trans- 
verse sections  of  the  finer  bronchial  branches. 

The  walls  of  the  air-vesicles  (fig.  266,  b)  are  rather  thin  and 
consist  of  elastic  fibres  (a).      Between  the  latter  there  is  a 


Fig.  266.  Section  through  the  lungs  of  a  child  9  months  old.  Elastic  trabeculaj  (a)  between 
the  alveoli,  6  ;  d,  capillary  vessels  curved  in  a  tendril-like  manner ;  c,  remains  of  the  simple  pave- 
ment epithelium  of  the  alveoli. 

homogeneous  connective  substance,  which  is  also  to  be  recog- 
nized as  a  limiting  layer  towards  the  cavity.  These  walls  are 
without  muscular  elements,  as  any  one  will  be  convinced  by 
treating  them  with  chloride  of  palladium. 

We  meet  with  a  wonderfully  rich  network  of  capillaries, 
the  meshes  of  which  are  small,  but  vary  in  size  with  the  degree 
of  distention  of  the  alveoli  (figs.  267  c,  266 '  d).  There  are  one, 
two,  or  three  small,  very  transparent,  rounded  and  polygonal 


RESPIRATORY    ORGANS.  491 

nucleated  cells  (fig.  267  tf,)  lying  in  each  of  the  meshes  ac- 
cording to  its  size.  In  transverse  sections  of  the  pulmonary 
vesicles,  the  epithelial  cells  are  seen  to  spring  forward  in 
a  slightly  convex  manner  into  their  cavities.  Very  dilute 
acetic  acid  may  also  be  used  to  demonstrate  their  nuclei ; 
it  should  not  be  too  concentrated,  as  a  free  nuclear  formation 
remains  which  has  been  erroneously  taken  for  nuclei  of  the 
alveolar  tissue.  Frequent  use  of  the  silver  impregnation  has 
also  been  made  of  late,  and  the  occurrence  of  large,  non-nucle- 
ated cells  over  the  capillary  walls  (fig.  268)  has  been  recognized 
with  its  assistance,  so  that  the  appearance  of  a  connected  epi- 
thelium is  presented  (Elenz,  F.  E.  Schulze,  and  others). 


Fig.  267.     A  pulmonary  alveolus  of  the  Fig.  268.     Pulmonary  epithelium  of  an 

calf,     a,   larger  blood-vessel ;  6,   capillary  adult  cat,  after  Elenz. 

network;  c,  epithelial  cells. 

If,  therefore,  a  simple  tessellated  epithelium  is  certainly 
present  in  the  lungs,  we  must  assume  that,  though  it  is  inter- 
rupted, it  nevertheless  occurs  in  a  modified  form  over  the 
tubes  of  the  capillary  network,  and  may,  therefore,  be  con- 
tinuous. 

But  we  must  again  have  recourse  to  the  injected  preparation 
(figs.  266,  267).  If  a  portion  of  the  capillary  network  be 
regarded  from  the  surface,  the  wavy  undulations  and  loop -like 
curves  of  the  vessels  are  seen.  If  viewed  from  the  side,  the 
tendril-shaped  curves  are  seen  to  pass  more  or  less  beyond  the 
walls  of  the  alveoli,  according  to  the  degree  of  distention  of  the 
latter,  so  that  they  often  project  into  the  air- vesicles  as  loops 


492  SECTION   NINETEENTH. 

of  considerable  size,  projections  which,  in  pathological  con- 
ditions, may  be  met  with  in  a  much  higher  degree  (Buhl). 

*  The  numerous  lymphatics  of  the  lungs  are  to  be  injected  by 
the  puncturing  method.  A  single-layered  network  with  large 
meshes  is  found  beneath  the  pleura ;  this  communicates  with 
the  deeper  lymphatics  accompanying  the  bronchi  by  means  of 
branches  which  pass  between  the  lobules  toward  the  interior  of 
the  organ.  The  commencement  of  the  lymphatics  appears  in 
the  walls  of  the  pulmonary  vesicles  in  the  horse,  in  the  form 
of  lacuna-like  dilatations  (Wy  wodzoff). 

The  nerves  of  the  lungs  pursue  the  same  course  as  the  bron- 
chi and  vessels  (especially  the  pulmonary  artery),  and  may  be 
followed  deep  into  the  interior,  of  the  organ.  Microscopic  gan- 
glia occur  at  the  points  where  their  branches  are  given  off. 
The  treatment  with  chromic  acid  or  diluted  pyroligneous  acid 
serves  for  their  primary  recognition;  osmic  acid  may  be  recom- 
mended for  more  accurate  studies. 

The  gland-like  structure  of  the  whole  organ  may  be  recog- 
nized in  a  beautiful  manner  in  foetal  lungs,  especially  those  of 
embryos  from  the  first  half  of  intra-uterine  life.  After  being 
hardened  in  alcohol,  thin  sections  are  to  be  made  and  carefully 
stained ;  in  these  the  covering  of  cylindrical  epithelium  of  the 
glandular  canals  and  the  connective-tissue  framework  (Darmfa- 
serblatt  of  Remak)  are  easily  seen. 

Numerous  structural  changes  of  the  respiratory  organs,  espe- 
cially of  the  lungs,  come  under  the  observation  of  the  physician. 
The  methods  of  investigation  are  either  the  same  as,  or  quite 
similar  to,  those  for  the  normal  organ.  Some  of  these  condi- 
tions, which  present  considerable  microscopical  interest,  may 
here  be  briefly  mentioned. 

Pigmentations,  that  is,  collections  of  fine  melanine  granules, 
which  give  the  organ  a  spotted  appearance,  are  met  with  in  all 
human  lungs  after  a  certain  period  of  life,  so  that  they  are  to  be 
denoted  as  normal  occurrences.  They  sometimes  lie  in  the  in- 
ter-alveolar elastic  tissue,  sometimes  in  the  connective-tissue  in- 
terstitial substance  of  the  pulmonary  lobules.  The  cells  of  the 
alveolar  epithelium  may  also  undergo  this  pigmentation,  and, 
evacuated  by  coughing,  occur  in  the  sputum  (p.  498),  as  in 


EESPIEATORY    ORGANS.  493 

other  cases  they  are  found  to  have  undergone  fatty  degenera- 
tion. 

Kow  where  do  these  black  molecules  originate  ?  They  are — 
and  we  may  at  the  present  time  assert  it  with  confidence — of  a 
double  origin.  They  may  consist  of  the  ordinary  dark  pigment 
of  the  organism,  of  melanine.  Here,  as  in  the  bronchial  glands 
(p.  399),  the  cause  may  be  small  apoplectic  effusions  from  the 
pulmonary  capillaries,  which  are  so  readily  surcharged  with 
blood;  likewise  transudations  of  dissolved  hsematine  into  the 
tissue.  Then  also,  in  civilized  life,  the  individual  surrounded 
by  smoke  and  soot  inspires  the  finest  particles  of  coal.  They 
penetrate  into  the  cell -bodies  of  the  alveolar  epithelium,  then 
into  the  lung-tissue,  and  from  here '(probably  with  the  aid  of 
migratorially  inclined  lymphoid  cells)  into  the  bronchial  glands. 
This  condition,  anthracosis,  may  be  artificially  induced  in  mam- 
malial  animals  by  shutting  them  up  in  a  sooty  room  (Knauir). 
Coal-workers  show  the  highest  degree  of  the  disease.  Another 
observation  of  Zenker's  is  very  interesting.  Operatives  in  fac- 
tories where  they  have  much  to  do  with  oxide  of  iron,  present 
exactly  the  same  condition  of  the  lungs,  only  everything  is  red 
instead  of  black. 

A  senile  alteration  of  the  pulmonary  tissue  and  of  the  alveoli, 
which  accompanies  the  atrophy  of  the  capillaries,  consists  of 
the  disappearance  of  the  walls  of  some  of  the  air- vesicles,  and  the 
union  of  several  of  these  into  larger  cavities.  To  prepare  such 
lungs  for  examination  they  should  be  inflated  and  dried  ;  in  cer- 
tain cases  the  blood  and  air  passages  may  be  previously  injected. 

Pathological  new  formations  of  the  lungs  still  give  rise  to 
many  difficulties  for  the  microscopist,  especially  in  recognizing 
the  normal  cellular  elements  of  the  organ  from  which  the  for- 
mer take  their  origin. 

The  lymphoid  cells  which  have  emigrated  from  the  blood- 
vessels are  represented  here  also,  at  least  in  part,  by  the  pus- 
corpuscles.  Such  an  extravasation  of  these  cells  appears  to  be 
very  much  facilitated  in  the  pulmonary  alveoli,  where  the  so 
numerous  vessels  are  covered  only  by  a  thin  layer  of  epithe- 
lium. They  may  also  occur  here  in  the  interior  of  cylindrical 
or  irregularly  formed  epithelial  cells,  probably  having,  however, 


494  SECTION   NINETEENTH. 

only  penetrated  from  without,  and  not  having  been  produced  in 
the  latter. 

The  generally  more  rapidly  progressing  inflammation  of  the 
pulmonary  tissue,  the  so-called  croupous  pneumonia,  shows  at 
the  commencement  a  considerable  distention  of  the  respiratory 
capillary  network,  then  a  filling  up  of  the  alveoli  and  inf  undi- 
bula  with  coagulated  fibrin,  as  well  as  with  extravasated  red  and 
colorless  blood-cells.  Later  the  lung-tissue  proper  also  becomes 
infiltrated  with  cells.  The  softened  mass  is  at  last  met  with 
under  the  form  of  pus.  The  role  which  the  alveolar  epithelium 
plays  in  this  disease  still  remains  to  be  investigated. 

The  primary  microscopical  appearances  of  the  above-men- 
tioned contents  of  the  air-passages  in  a  case  of  pneumonia  may 
be  obtained  by  scraping  the  cut  surfaces.  For  closer  examina- 
tion the  tissue  is  to  be  carefully  hardened  in  solutions  of  chro- 
mic acid  of  increasing  concentration,  in  Miiller's  fluid,  or 
absolute  alcohol.  Injections  of  the  vessels  of  inflamed  lungs  do 
not  readily  succeed,  in  consequence  of  the  distention  of  the 
alveoli  and  the  numerous  lacerations  of  the  capillaries. 

Tuberculosis  of  the  lungs  is  of  extremely  frequent  occur- 
rence, partly  in  the  form  of  so-called  tuberculous  infiltration, 
partly  in  the  form  of  scattered  aggregations  and  numberless 
small  nodules.  Yery  many  investigations  have  been  made  of 
this  matter,  and  much  has  been  written  about  it,  but  our  knowl- 
edge of  the  subject  still  leaves  much  to  be  desired.  Although 
it  is  well  established  that  the  tubercular  substance  is  formed  of 
shrunken  nuclei  and  cells,  and  from  the  fragments  of  these 
structures  and  a  fine  granular  matter,  and  that  the  neighboring 
vessels  which  lie  between  them  also  become  atrophied,  the  point 
of  ori  in  still  remains  uncertain.  The  alveolar  epithelium  is 
certainly  frequently  concerned  in  this  process,  and  hence  the 
position  of  the  tubercular  mass  within  the  alveoli  is  readily 
accounted  for.  On  the  other  side,  however,  the  tissue  of  the 
lung  itself  gives  rise  to  such  masses.  In  consequence  of  the 
absence  of  connective-tissue  corpuscles  from  the  walls  of  the 
alveoli,  and  the  sparseness  of  this  tissue  between  the  primary 
lobules,  attention  should  be  directed  firstly  to  the  emigration  of 
the  lymphoid  cells,  and  secondly  to  the  cells  of  the  capillary 


EESPIKATOKY    OEGA^S.  495 

vessels  and  the  adventitia  of  the  finer  blood-vessels  ;  and,  in  fact, 
recent  investigations  have  discovered  such  a  point  of  origin  of 
the  miliary  tubercles. 

The  proliferations  of  the  nuclei  of  vessels  which  have  been 
noticed  by  several  observers  to  take  place  in  such  cases  are 
rendered  all  the  more  probable  from  the  fact  that  a  quite  simi- 
lar process  occurs  in  the  adventitia  of  similar  vessels  of  the 
brain,  and  also  leads  to  the  formation  of  miliary  tubercle. 
Further  investigations  appear  to  be  necessary  to  determine 
whether  the  nuclei  of  the  true  primary  capillary  membrane  are 
also  capable  of  undergoing  such  a  metamorphosis.  How  import- 
ant for  all  such  investigations  the  previous  injection  of  the  blood- 
vessels with  transparent  masses  is,  it  is  unnecessary  to  mention. 
For  hardening,  chromic  acid  is  to  be  used,  commencing  with 
weaker  solutions  (0.1-0.2  per  cent.),  and  then  passing  to  those 
which  are  stronger  (0.5-1  per  cent.) ;  Miiller's  fluid  or  absolute 
alcohol ;  the  organ  should,  naturally,  be  immersed  in  small  pieces. 

We  must  leave  the  further  consideration  of  these  masses  of 
tubercle  to  the  text-books  on  pathological  anatomy.  The  sub- 
stance we  have  described  usually  becomes  softened  and  leads  to 
the  formation  of  cavities,  in  consequence  of  the  destruction  of 
the  tissue  of  the  lung.  If  we  examine  the  contents  of  such  a 
cavern  we  find  softened  tuberculous  matter,  pus-cells,  blood- 
corpuscles,  blood  coagula,  and  elastic  fibres.  The  latter  may 
be  coughed  up  and  appear  in  the  sputum  and  thus  confirm  the 
diagnosis.  We  shall  return  to  this  point.  The  walls  of  these 
caverns  are  seen  to  be  formed  of  compressed  lung-tissue. 

The  examination  of  the  fresh  tissue  of  the  pleura  may  be 
made  by  scraping  the  epithelium  and  tearing  the  connective 
tissue  of  the  serous  membrane,  with  the  assistance  of  the  usual 
reagents.  Thin  sections  may  also  be  made  from  hardened 
preparations.  These  methods,  besides  being  used  for  the  other 
serous  sacs  of  the  body,  as  the  pericardium  and  peritonaeum, 
may  also  be  employed  for  the  examination  of  pathological  con- 
ditions. , 

Effusions  of  a  watery  or  purulent  nature  are  to  be  treated  in 
the  same  way  as  other  fluids  which  contain  cells ;  more  solid 
masses  of  exudation,  which  show  rounded  cells  enclosed  in  coag- 


496 


SECTION    NINETEENTH. 


ulated  fibrine,  are  to  be  examined  partly  fresh,  partly  in  sections 
from  the  hardened  preparation.  The  new  formations  of  con- 
nective tissue  in  the  form  of  looser  or  firmer  bands,  which  unite 
both  walls  of  the  pleura,  require  no  further  mention,  as  they 
are  to  be  investigated  in  the  same  manner  as  connective  tissue. 
The  masses  expelled  by  hawking  or  coughing  are  called 
sputa.  They  do  not  originate  exclusively  from  the  respiratory 
organ,  however,  as  matters  from  the  mouth  as  well  as  from  the 
posterior  nares  may  become  mixed  with  the  products  furnished 
by  the  respiratory  apparatus.  In  the  examination  of  the  sputa, 
therefore,  we  must  always  expect  to  find  not  only  the  elements 
of  the  respiratory  apparatus,  but  also  the  epithelium  of  the  two 
systems  of  cavities  mentioned,  fragments  of  food  which  have 
remained  in  the  mouth,  grains  of  starch,  for  example,  the  Lepto- 
thrix  buccalis,  etc. 

The  microscopical  treatment  is,  on  the  whole,  very  easy.  The 
specimen  for  examination  is  to  be  obtained,  according  to  its 
consistence,  either  with  a  glass  rod,  or,  if  pretty  tough,  by 
means  of  the  forceps  and  scissors ;  it  is  then  to  be  examined 
floating  in  its  natural  fluid  with  a  power  of  medium  or  greater 

strength.  Reagents  are  to  be  em- 
ployed as  circumstances  may  require, 
though  their  action  may  be  impeded, 
it  is  true,  by  the  mucus  of  the  fluid. 
It  is  relatively  difficult,  however, 
to  preserve  such  objects  as  perma- 
nent specimens.  The  attempt  may 
be  made  to  preserve  them  in  cam- 
phor-water, very  dilute  solutions  of 
chromic  acid,  the  Pacinian  or  some 
similar  fluid  (pp.  213  and  214). 

The  constituents  of  the  sputum 
(fig.  269)  are,  together  with  en- 
tangled air-bubbles,  epithelium,  the 
cellular  elements  of  glands,  mu- 
cous and  pus  cells,  blood-corpuscles, 

pigmentated  cells,  those  in  a  condition  of  fatty  degeneration, 
and  fragments  of  pulmonary  tissue.     Crystals  rarely  occur  and 


Fig.  269.  Elements  of  the  sputum. 
a,  mucous  and  pus  corpuscles  ;  &,  so- 
called  granule  cells;  c,  with  black 
pigment  (alveolar  epithelium);  d, 
blood-cells ;  e,  ciliated  cells  after  the 
loss  of  the  cilia  and  such  a  cell  with 
cilia ;  /,  spherical  ciliated  cell  in 
catarrh  of  the  respiratory  passages ; 
g,  ciliated  cells  which  have  pus  cor- 
puscles in  their  interior  ;  A,  pulmo- 
nary fibres. 


EESPIEATOEY    ORGANS.  497 

are  of  minor  importance.  We  find  the  organized  constituents 
either  unchanged  or  more  or  less  altered  by  the  action  of  en- 
dosmosis  and  of  maceration. 

The  pavement  epithelium  is  derived  from  the  mucous 
membrane  of  the  cavity  of  the  mouth,  but  a  few  such  cells 
may  also  come  from  the  larynx,  where  they  cover  the  lower 
vocal  cords.  Smaller  pavement  or  rounded  cells  come  in  part 
from  the  glands  of  the  mucous  membrane,  and  in  part,  doubt- 
less, from  the  alveoli  of  the  lungs,  although  it  is  scarcely  possi- 
ble to  recognize  the  latter  with  certainty  in  sputum.  The 
quantity  of  this  pavement  epithelium  from  the  mucous  mem- 
brane is  naturally  quite  variable.'  The  tough  masses  which 
many  persons  are  accustomed  to  hawk  up  in  the  morning  are 
as  a  rule  rich  in  them ;  their  number  also  increases  in  the  spu- 
tum when  the  digestive  organs  are  in  an  irritated  condition. 
Ciliated  cells,  which  occur,  however,  by  no  means  frequently  in 
the  sputum,  originate  in  part  from  the  posterior  portion  of  the 
olfactory  organs,  in  part,  and  chiefly,  from  the  respiratory 
passages.  They  may  be  met  with  entirely  unchanged  in  form 
(e)  or,  which  is  more  frequently  the  case,  after  their  ciliae  have 
fallen  off  (e  g).  At  the  commencement  of  catarrhal  affections 
of  the  air-passages  one  may  see,  here  and  there,  cells  coughed 
up  which  still  vibrate,  partly  in  their  normal  shape  (e  below), 
and  partly  changed  to  spherical  shapes  (f ).  The  nuclei  appear 
either  single  or  we  notice  a  few  granulated  structures  (g\  which 
are  probably  mucous  and  pus  corpuscles  within  the  cylindrical 
cells,  so  that  migratory  conditions  of  these  cells,  similar  to  those 
we  have  formerly  mentioned,  are  probably  also  repeated  here. 
Then  the  granulated  elements  designated  as  mucous  corpuscles 
(a)  are  also  found  in  all  sputa.  Their  number,  and  with  them 
the  appearance  of  the  sputum,  is  subject  to  very  great  variations. 
If  the  latter  be  yellow  and  thickened,  the  number  of  the  former 
structures  is  enormous,  and  one  then  speaks  of  pus-corpuscles. 
It  is  evident  that  this  most  extensively  disseminated  element  of 
the  sputum  is  to  be  met  with  changed  in  many  ways,  which  is 
due  in  part  to  endosmotic  influences  and  to  maceration,  as  well 
as  to  the  various  stages  of  life  of  the  cell.  Dark,  granulated 
cells,  overloaded  with  molecules  of  fat,  are  considered  as  older 
32 


498  SECTION   NINETEENTH. 

forms,  and  this  view  is  certainly  correct.  Larger  structures, 
with  similar  fat-like  contents,  are  partly  due  to  pus-corpuscles, 
"but  partly  also  to  changes  of  the  alveolar  epithelium.  The 
name  of  granule  cells  or  inflammatory  globules  (£)  was  formerly 
given  them.  Their  physiological  prototypes  are  represented  by 
many  gland-cells  overloaded  with  fat  (sebum  cutaneum,  colos- 
trum). 

Similar  spherical  cells  may  contain  a  brown,  still  somewhat 
soluble  pigment,  though  they  are  of  rare  occurrence.  The  same 
cells  with  black  pigment  granules  (c)  form  more  frequent  con- 
stituents. They  are  observed  in  more  severe  diseases  of  the 
lung-tissue,  but  also  in  simple  catarrhal  irritations.  They  are 
degenerated  alveolar  epithelium  (p.  492). 

On  a  previous  page  we  mentioned  the  quite  superficial  posi- 
tion of  the  pulmonary  capillaries.  We  can  easily  understand 
that  the  red  blood-corpuscles  readily  pass  out  through  the 
uninjured  capillary  walls,  and  that  the  latter  also  frequently 
become  ruptured  in  consequence  of  their  over-distention  with 
blood,  and  hence  the  frequent  occurrence  of  blood-corpuscles 
in  the  sputum  (d).  According  to  the  quantity  of  the  former, 
the  latter  appears  to  the  naked  eye  either  as  blood  or  as  spotted 
and  striped  with  blood,  or,  if  the  mixture  be  more  intimate, 
more  of  a  yellow,  reddish,  or  rust  color.  Yery  small  quantities 
of  blood-cells  are  only  to  be  found  with  the  aid  of  the  micro- 
scope. The  blood  is  either  still  fluid  or  coagulated,  and  then 
the  cells,  together  with  other  structures,  are  concealed  in  the 
fibrous  coagulum.  They  sometimes  appear  entirely  unchanged, 
with  the  familiar  depression  in  their  centres  (p.  230),  sometimes 
shrunken  and  in  a  crenated  form,  or,  finally,  swollen  into  a 
globular  shape,  and  then,  not  unfrequently,  they  are  in  various 
stages  of  discoloration.  One  sees  in  part  single  cells,  in  part 
lumpy  aggregations,  and  in  part  the  familiar  groups  resembling 
rolls  of  coin  (with  which  fig.  89,  p.  235  is  to  be  compared). 
The  most  frequent  arrangement  of  the  blood-corpuscles  in 
the  sputum  is  such,  however,  that  the  borders  of  the  cells  touch 
each  other.  The  tough  mucus  may,  finally, — and  this  change 
of  their  form  is  frequently  met  with, — tear  the  soft  blood-corpus- 
cles considerably. 


EESPIEATOBY    ORGANS.  499 


The  presence  of  elastic  fibres  and  shreds  of  elastic  membrane 
in  a  sputum  is,  finally,  of  greater  importance  to  the  practical 
physician  for  the  purposes  of  diagnosis.  If  these  are  not  frag- 
ments of  food,  which  is  sometimes  the  case,  they  indicate  a 
destruction  of  the  pulmonary  tissue  in  consequence  of  softened 
tubercle  or  gangrene.  Still,  they  are  by  no  means  of  frequent 
occurrence  in  the  former  widely  disseminated  disease,  so  that 
their  absence  from  the  expectoration  does  not  possess  any 
negative  importance.  One  finds  in  part  single  fibres,  in  part 
several  lying  near  each  other,  or  also  hanging  together  like  a 
network  (fig.  269  h).  The  difficult  solubility  of  these  structures 
and  their  entire  optical  relations  secure  those  who  are  some- 
what practised  from  any  danger  of  mistaking  them.  The 
beginner  might,  accidentally,  mistake  threads  of  lint  and  the 
like  for  them,  and  it  would  therefore  be  well  for  him  to  con- 
sult an  experienced  observer.  A  highly  meritorious  observer, 
Eemak,  has  long  since  given  us  a  good  method  for  finding  the 
lung-fibres.  Each  sputum  that  the  patient  coughs  up  should 
be  placed  by  itself  on  a  dish  or,  where  the  whole  expectorated 
mass  is  obtained  for  examination,  it  is  to  be  placed  in  a  glass 
cylinder  filled  with  water,  and  smartly  shaken.  The  masses 
thus  separated  will,  after  a  short  time,  form  a  sediment,  and  in 
this  the  fibres  in  question  are  to  be  sought  for. 

Crystals  of  the  ammonio-phosphate  of  magnesia  as  well  as 
needle-shaped  concretions  of  fatty  substances  may  be  met  with 
in  decomposed  masses  of  sputum.  Tablets  of  cholesterine  are 
rare. 

We  cannot  leave  the  respiratory  apparatus  before  having 
made  mention  of  two  organs  lying  in  its  neighborhood,  the 
thyroid  and  thymus  glands. 

The  thyroid  gland,  an  organ  which  is  entirely  enigmatical  in 
its  physiological  regard,  belongs  to  a  naturally  related  series  of 
gland-like,  ductless  structures,  to  which,  in  the  human  body,  we 
also  reckon  the  supra-  renal  capsules  and  the  hypophysis  cerebri. 
Although  it  does  not  share  with  these  organs  the  near  relation- 
ship with  the  nervous  system,  it  nevertheless  agrees  in  this, 
especially  with  the  supra-renal  capsules,  that  it  is  also  subjected 
to  an  earlier  senescence,  and,  like  the  latter,  is  met  with  in  the 


500 


SECTION    NINETEENTH. 


adult  body  in  a  condition  of  retrograde  metamorphosis.  While, 
however,  the  supra-renal  capsule  undergoes  fatty  infiltration, 
the  thyroid  gland  presents  another,  namely,  the  colloid  meta- 
morphosis, the  commencement  of  which  may,  indeed,  begin 
even  at  the  end  of  embryonic  life. 

The  framework  of  the  thyroid  gland  (fig.  270  a)  consists  of 


Fig.  270.  Portion  of  the  thyroid  gland  of  a  child,    fl,  the  connective-tissue  framework ;  6,  the 
rounded  cells  of  the  inner  surface,  lined  with  epithelium  (<"). 

an  ordinary  fibrillated  connective  tissue  intermingled  with  elas- 
tic fibres,  which  is  permeated  by  numerous  vessels  and  a  not 
inconsiderable  number  of  lymphatic  canals.  It  encloses  groups 
of  rounded  cavities  (l>)  in  which  an  especial  membrana  propria 
is  wanting  (p.  408).  From  these  groups  are  formed  the  lobules, 
and  from  the  latter  the  larger  lobes. 

A  foetal  thyroid  gland,  or  one  which  is  not  as  yet  altered, 
shows  the  cavity  lined  by  a  layer  of  nucleated  cylindrical  cells 
(c)  which  are  shorter  and  more  flattened  against  each  other,  and 
within  the  same  a  homogeneous  viscous  fluid.  The  cavity  is 
surrounded  by  a  close  capillary  network  which  is  easily  injected 
from  the  artery.  In  the  connective  tissue  of  a  group  of  cavities 
run  fine  canals,  originating  in  the  numerous  superficial  lympha- 
tic vessels  with  valves,  forming  sometimes  closed,  sometimes 
irregular  circular-shaped,  sometimes  only  arched  columns.  Still 
finer  lymphatic  canals  not  unfrequently  pass  between  a  few 


EESPIRATOKY    OEGANS. 


501 


cavities.  Their  injection  may  also  be  readily  accomplished  by 
means  of  the  customary  puncturing  method  in  the  new-born 
and  the  child,  in  the  dog  and  the  rabbit. 

Hardening  in  chromic  acid  or  alcohol  serves  for  the  prepara- 
tory treatment.  Thin  sections  show  many  things  more  beauti- 
fully after  tingeing  than  in  an  uncolored  condition.  The  frame- 
work is  easy  to  isolate  by  brushing.  The  thyroid  gland  of  the 
calf,  macerated  in  pyroligneous  acid,  is  to  be  recommended  for 
the  recognition  of  the  nerves  (Peremeschko).  Osmic  acid  has 
not  afforded  us  here  any  results  worthy  of  mention. 

In  the  place  of  the  viscous  fluid  mass  there  occurs  (and  it 
is  indeed  frequently  noticed  even  in  the  bodies  of  new-born 
children),  together  with  dilatations  of  the  glandular  cavities, 
another  homogeneous,  more  solid  contained  matter,  the  colloid, 
a  modified  albuminous  substance  (fig.  271).  It  is  formed  by  the 
metamorphosis  of  the  cell-contents  of  the  epithelium,  whereby 
the  cells  are  destroyed.  We  have  already  mentioned  the  colloid 
degeneration,  which,  though  not  constituting  a  very  frequent 
occurrence,  appears  in  the  similarly  formed  hypophysis  cerebi, 
also  attacks  the  cells  of  carcinomatous 
neoplasms,  and  may  give  rise  to  colloid 
carinoma  (p.  285).  In  the  slighter  de- 
grees, the  dilatation  of  the  cavities,  and 
the  compression  of  the  interstitial  con- 
nective tissue  coincident  therewith,  is 
moderate,  so  that  although  narrowed,  and 
here  and  there  atrophied,  the  lymphatic 
passages  may  be  rendered  apparent  by 
injection.  The  capillary  network  retains 
the  old  permeability,  and  the  ephithelial 
cells  still  appear  preserved. 

Higher  degrees  of  this  colloid  meta- 
morphosis show,  together  with  an  in- 
crease of  volume,  that  the  whole  organ 
is  permeated  by  transparent,  sometimes 
smaller,  sometimes  larger  colloid  lumps. 

The  epithelium  of  the  distended  cavities  has  disappeared,  and 
the  compression  of  the  connective  tissue  has  become  such  that, 


Fig.  271.  Colloid  metamor- 
phosis, o,  Gland  vesicle  of  the 
rabbit ;  6,  commencing  colloid 
metamorphoses  of  the  calf. 


502  SECTION    NINETEENTH. 

though  the  blood  still  passes,  an  impermeability  for  the  lymph 
has  taken  place.  All  attempts  at  injection  remain  unsuccessful, 
and,  from  the  nature  of  the  colloid  matter,  a  resorption  through 
the  capillary  walls  is  no  longer  to  be  thought  of.  Thus  arises 
the  goitre,  that  disease  which  is  still  so  obscure  in  its  etiological 
relations. 

With  further  accumulations  of  the  colloid  masses  the  connec- 
tive-tissue interstices  disappear,  and  as  the  excavations  unite, 
these  masses  become  joined  together.  In  this  way  larger  and 
larger  spaces  become  filled  with  such  masses,  and  the  connective- 
tissue  stroma  lying  between  them  appears  as  if  macerated.  An 
entire  lobe  may  finally  present  a  single  collection  of  colloid. 

Sections  of  the  injected  organ,  deprived  of  their  water  by 
means  of  absolute  alcohol,  may  be  mounted  in  Canada  balsam ; 
the  remaining  preparations  are  to  be  mounted  moist  in  dilute 
glycerine. 

Not  less  obscure  in  its  function  and  in  its  structure,  the  thymus 
appears,  at  the  present  time,  to  be  not  entirely  comprehensible. 
It  also  undergoes,  although  later,  a  transformation,  that  is,  a 
metamorphosis  into  fat-tissue. 

The  elements  which  constitute  the  lobes  of  our  organ  have 
been  described  by  authors  as  granules  or  acini.  They  remind 
one  in  their  texture  of  a  lymphatic  follicle,  and  show  the  same 
connective-tissue  reticular  framework,  with  nuclei  at  the  nodal 
points  and  permeated  with  capillaries ;  likewise  the  same  filling 
up  of  all  the  intervening  spaces  by  an  innumerable  quantity  of 
lymphatic  cells.  Nevertheless,  a  more  thorough  investigation 
also  reveals  many  deviations.  In  fine,  transverse  sections  of 
hardened  organs  the  thymus  follicle  contains  in  its  centre  a  cav- 
ity filled  with  a  cloudy  fiuid,  the  further  explanation  of  which 
is  obtained  by  side  views.  In  such,  cul-de-sac-like  ducts  appear 
to  come  from  the  follicle,  and  these  canals  from  each  lobe  be- 
come conjoined  below.  Herein  lies,  according  to  my  view,  the 
rudiment  of  the  further  diverticulated,  foetal  thymus-gland  tube, 
and  not  a  lymphatic  canal-work,  as  His,  in  a  beautiful  work, 
has  declared  the  same  to  be.  Firstly,  notwithstanding  numer- 
ous attempts,  it  has  not  been  possible  for  us  to  accomplish  a 
lymph  injection  of  the  organ  and  of  these  passages  ;  then — and 


RESPIRATORY    ORGANS.  503 

upon  this  point  greater  weight  may  be  laid — the  more  recent 
investigations  have  demonstrated  entirely  different  arrange- 
ments of  the  lymphatic  channels  in  the  lymphoid  follicles.  A 


Fig.  272.  Portion  of  the  calf  B  thymus,  after  His.     The  rings  of  the  arterial  branches  (a)  and 
venous  branches  (6),  with  the  capillary  network  (c)  and  the  cavities  of  the  acini  (d). 

delicate  vascular  network  (but  also  not  entirely  corresponding 
to  the  ordinary  arrangement  of  that  of  the  lymphatic  follicles) 
permeates  the  follicles  of  the  thymus.  In  the  calf  (fig.  272) 
the  peripheral  portion  of  the  latter  is  surrounded  in  a  circular 
manner  by  arterial  (a)  and  venous  (£)  branches,  and  the  capil- 
lary network  (c)  resembles  that  of  a  Peyerian  follicle,  but  natu- 
rally bends  with  all  its  tubes  around  the  central  canal  (d)  in  a 
loop-like  manner  (His).  In  the  human  thymus,  on  the  con- 
trary, the  arterial  branches  run  in  the  interior  of  the  lobules 
and  follicles.  The  venous  ring  of  the  latter  remains,  however, 
the  same  as  in  the  calf. 

Some  time  after  birth  (pretty  early  in  well-nourished  calves, 
probably  much  later  in  man)  commences  an  extensive  transfor- 
mation of  the  stellate  cells  of  the  thymus  stroma  into  globular 
fat-cells,  and  of  the  neighboring  reticular-fibres  into  a  more  ho- 
mogeneous matter  which  envelops  the  latter.  Th£  microscopic 
examination  shows  interesting  transformations  of  the  capillary 
network  and  a  gradual  disappearance,  frequently  united  with 
fatty  degeneration,  of  the  lymph-cells  of  such  metamorphosed 


504  SECTION    NINETEENTH. 

localities.     A  quite  similar  process  may  also,  as  I  have  shown, 
attack  the  follicles  of  the  lymphatic  glands. 

Peculiar  structures  of  the  contents  of  the  thymus  are  pre- 
sented by  the  so-called  concentric  corpuscles.  Their  stratified 
investment  consists,  according  to  Paulitzky,  of  pavement-shaped 
epithelial  cells  (comp.  p.  265). 

The  methods  for  examining  the  thymus  gland  are  various. 
For  hardening,  use  at  first  very  watery,  later  somewhat  stronger 
solutions  (chromic  acid  from  0.1-0.2,  then  from  0.5  per  cent., 
chromate  of  potash  in  corresponding  strength,  strongly  diluted 
alcohol).  Only  in  this  way  can  the  reticular  framework  be 
brushed  out  over  larger  distances.  Increased  hardening  leads 
to  the  recognition  of  the  passages  described,  and  of  the  walls  of 
the  blood-vessels. 

Kolliker  recommends  boiling  in  ordinary  water  to  render  the 
canal- work  of  the  thymus  visible.  Subsequently  hardened  in 
alcohol,  such  organs  are  said  to  permit  of  good  sections  being 
made ;  that  observer  also  recommends  the  boiling  of  this  organ 
in  vinegar. 

The  blood-vessels  are  not  very  easy  to  inject,  as  it  is  always 
necessary  to  ligate  a  number  of  them,  or  to  compress  them  with 
the  sliding  forceps.  An  opaque  mass,  chrome-yellow,  for  ex- 
ample, is  very  handsome  for  review  preparations  (which  may  be 
mounted  dry) ;  for  histological  purposes  select  carmine  and 
Prussian  blue.  Watery  glycerine  serves  for  their  preservation. 

It  has  already  been  remarked  above  that,  thus  far,  attempts 
at  injection  have  not  shown  any  lymphatics  in  the  interior. 
May  another  be  more  fortunate,  and  thus  elucidate  in  this 
structural  relation  that  organ  which,  as  the  at  present  last  of  its 
species,  must  awake  the  interest  of  histologists. 


Section 


URINARY  ORGANS 

THE  investigation  of  the  urinary  apparatus,  and  especially  of 
the  secretion  produced  by  it,  lays  claim  in  a  high  degree  to  the 
interest  of  the  medical  world  ;  indeed,  the  signification  of  the 
urine  at  the  sick-bed  has  been  valued  for  thousands  of  years, 
and  often  also  overestimated  in  the  most  ridiculous  manner. 

The  kidney,  as  is  known,  constitutes  the  most  important 
organ  of  the  urinary  apparatus. 

An  external  brown-red  mass,  the  cortical  substance,  envelops 
in  the  mammalia  and  man  an  internal,  paler  mass,  the  medul- 
lary substance,  which  presents  even  to  the  naked  eye  a  radiated 
fibrous  appearance.  The  latter,  in  most  mammalial  animals, 
enters  the  pelvis  of  the  kidney  with  a  single  ridge-shaped  point  ; 
but  is,  on  the  contrary,  in  man  (and  also  the  pig)  separated  into 
a  number  of  larger  conical-shaped  divisions  which  turn  their 
'points  towards  the  hilus.  These  are  the  so-called  Malpighiaii 
or  medullary  pyramids.  The  cortical  tissue  extends  down  be- 
tween the  lateral  surfaces  of  the  same  like  a  septum  (columnse 
Bertini).  A  connective-tissue  supporting  substance  permeates 
both  substances,  and  consequently  the  whole  organ. 

The  essential  conditions  of  the  finer  structure  of  the  kidney 
also  seemed  for  a  long  time  to  be  firmly  settled. 

The  radiated  fibrous  medullary  substance  was  regarded  by 
the  anatomists  and  physiologists  as  consisting  of  the  uriniferous 
canalicules  which  opened  free  at  the  pyramidal  points,  and 
which,  from  here,  with  numerous  acute-angled  divisions  and 
diminutions  in  size  induced  thereby,  passed  towards  the  cortical 
substance.  In.  passing  over  into  the  latter,  they  were  said  to 
lose  their  previous  rectilinear  direction,  to  assume  an  extremely 
complicated  tortuous  course,  and  finally,  enlarged  in  a  spherical 


506 


SECTION    TWENTIETH. 


manner,  to  terminate  as  capsules  of  the  Malpighian  vascular 
coils  (fig.  273.) 

Especially  after  Bowman,  in  the  year  1842,  had  discovered 
the  manner  of  termination  (or  origin)  of  the  urinif erous  canali- 
cules  just  mentioned,  the  structure  of  the  mammalian  kidney 
was  regarded  as  assured  and  near  to  a  conclusion. 


Fig.  273.  From  the  cortical  substance  of  the  human  kidney,  a,  Arterial  trunk  giving  off  the 
afferent  vessels  6,  of  the  glomerulus  c*,  c' ;  c,  efferent  vessels  of  the  latter ;  d,  the  capsule  of 
Bowman,  with  its  continuation  into  the  convoluted  uriniferous  canalicule  of  the  cortex  («). 

The  merit  is  due  to  Henle  of  having  brought  a  new  element 
of  agitation  into  this  subject.  He  discovered,  a  number  of 
years  ago,  in  the  medullary  substance  of  the  organ,  together 
with  the  long-known  open  uriniferous  canals,  a  system  of  finer, 
loop-shaped  passages  (which  turn  their  convexities  towards  the 
points  of  the  papillae).  He  also  succeeded,  in  several  mam- 
malial  animals,  in  injecting,  from  the  ureter,  the  straight  canals 
of  the  medullary  substance,  as  well  as  their  rectilinear  contiima- 


UEINAEY    OEGANS.  507 

tions  through  the  cortex  to  close  beneath  the  renal  capsules. 
As,  however,  all  attempts  to  inject,  from  these  passages,  the 
loop-shaped  canalicules  of  the  medulla  as  well  as  the  convo- 
luted ones  of  the  cortical  substance  failed,  this  savant  took — 
as  we  now  know,  erroneously — the  loop-shaped  passages  for  a 
system  of  closed  canals  not  connected  with  the  former,  and 
maintained  that  each  of  the  two  sides  of  the  loop  terminated, 
finally,  in  a  convoluted  tube  ending  in  a  Bowman's  capsule  in 
the  cortical  layer. 

Henle  came,  hereby,  in  conflict  with  several  older  reports 
of  injections,  which  told  of  successful  injections  of  the  entire 
canal- work  as  far  as  the  capsule  of  the  glomerulus,  in  mam- 
malial animals  and  in  man  (Geiiach,  Isaacs).  Neither  could 
the  (occasionally  easy)  injection  of  the  entire  canal-work  of 
the  kidney  from  the  ureter,  which  may  be  accomplished  in 
the  lower  vertebrates,  be  made  to  coincide  with  this  (Hyrtl, 
Frey). 

In  consequence  of  a  large  series  of  new  investigations  (among 
which  we  would  designate  the  work  of  Ludwig  and  Zawarykin, 
as  well  as  that  of  Schweigger-Seidel  as  the  most  important), 
Henle's  statements  have  been  modified  and  our  knowledge  of 
the  mammalial  kidney  not  inconsiderably  enlarged,  although 
even  now  there  are  still  many  points  in  the  structure  of  the 
kidney  remaining  to  be  investigated. 

The  primary  fundamental  view  of  the  structure  of  the  kidney 
may  be  obtained  with  any  mammalial  animal ;  the  most  con- 
veniently and  summarily,  it  is  true,  in  the  organs  of  very  small 
creatures  (Guinea-pig,  marmots,  moles,  quite  especially,  how- 
ever, the  bat  and  the  mouse). 

A  fine  longitudinal  section  from  the  medullary  substance  of 
the  fresh  organ  shows  the  open,  uriniferous  canalicules,  covered  ' 
by  a  transparent,  low,  cylindrical  epithelium,  and  a  distinct 
lumen.  Their  ramifications  may  be  represented  by  fig.  274 
(a  preparation  which,  however,  was  obtained  by  another 
method).  These  may  be  readily  distinguished  from  the  blood- 
vessels, if  the  latter  have  been  previously  injected  with  cold- 
flowing  Prussian  blue.  A  cautious  picking  apart  with  the  pre- 
paring needle  will  also  isolate  a  few  of  these  uriniferous  canali- 


508 


SECTION   TWENTIETH. 


cules,  and  lead  to  the  recognition  of  the  acute-angled  divi- 
sions. "With  a  sharp  razor  one  may  also 
succeed  in  obtaining  sufficiently  thin,  trans- 
verse sections  of  the  cortical  substance  to 
show  the  meandering  convolutions  of  their 
uriniferous  canalicules,  the  darker,  more 
granular,  thick  epithelium  of  the  latter,  the 
Bowman's  capsules,  and  (if  a  moderately 
large  amount  of  blood  has  remained)  the 
reddish-yellow  Malpighian  vascular  coils. 
The  latter  appear  most  beautifully  and 
sharply  with  all  artificial  injections. 

Even  here,  a  diligent  picking  enables 
the  observer  to  recognize  isolated  continu- 
ations at  least  of  the  uriniferous  canals  into 
the  widened  capsules  (fig.  273  e  d),  although 
this  communication  can  only  be  recognized 
with  difficulty  in  this  way.  The  most 
favorable  for  the  recognition  of  the  latter 
are  the  kidneys  of  the  lower  vertebrates, 
such,  for  example,  as  the  frog,  the  triton,  and  salamander 
(although  their  structure  is  not  the  same) ;  among  the  niam- 
malial  animals  I  would  most  recommend  the  organs  of  the 
mole.  The  gland-cells  become  transparent  by  the  addition  of 
alkalies,  and  their  structural  condition  is  not  unfrequently 
rendered  more  distinct. 

The  earlier  knowledge  of  the  kidney  was  obtained  in  this 
way,  and,  towards  the  close  of  the  first  half  of  this  century,  our 
information  concerning  the  same  remained  stationary  at  about 
this  stage. 

The  more  recent  times  have  made  us  acquainted  with  several 
other  very  important  methods  of  investigation.  Let  us  men- 
tion first  the  section  through  the  artificially  hardened  organ. 
Most  (and  especially  almost  all  pathologico-histologieal)  exam- 
inations are  at  present  made  in  this  manner.  Here  also  the 
freezing  method  proves  to  be  extraordinarily  conservative.  Re- 
course may,  furthermore,  be  had  to  chromic  acid,  its  potash-salt, 
or — which  is  best — to  absolute  alcohol.  We  obtain  in  this  maii- 


Fig.  274.  The  ramifica- 
tions of  a  uriniferous  canal 
from  the  medullary  sub- 
stance of  the  new-born  cat 
(muriatic  acid  preparation), 
a-c,  divisions  of  the  first  to 
the  fifth  order.  (Original 
sketch  by  Schweigger-Sei- 


URIKA.KY    OEGANS.  509 

ner,  without  trouble,  very  fine  and  instructive  longitudinal 
views  and — what  is  of  the  greatest  importance  for  many  textu- 
ral  conditions — good  representations  from  transverse  sections 
of  the  kidneys. 

We  would  also  recommend  here  the  previous  injection  of  the 
vessels,  in  small  kidneys,  with  cold  flowing,  in  more  voluminous 

organs,  with  solidifying,  transpa- 
rent masses.  The  slight  trouble 
will  be  richly  repaid  in  the  sub- 
sequent examination.  Staining 
methods  are  of  the  highest  value 
for  the  recognition  of  the  renal 
tissue  in  the  healthy  and  patho- 
logically altered  condition.  . 

In    the   medullary  substance 
.  we  again  recognize,  in  vertical 

Fig.  275.  Transverse  section  through  a  renal 

pyramid  of  the  new-born  child,  a  collective  sections,  the  relations  of  the  f  resh 
tabes  with  cylindrical  epithelium  ;  6,  descend- 

preparation;  in  transverse  sec- 
tions  (%-275),on  the  contrary,  the 
lumina  of  the  urinif  erous  canals, 

the  straight  ones  with  their  cylindrical  epithelium  (a)  as  well  as 
the  loop-shaped  ones  with,  for  the  most  part,  quite  flat  cells  (J), 
reminding  one  of  vascular  epithelium,  and  also  the  connective- 
tissue  stroma  of  the  medullary  substance  (e). 

Fine  longitudinal  sections  of  the  cortical  substance  (fig.  276) 
show,  on  the  contrary,  how  this,  the  stratum  of  the  convoluted 
uriniferous  canals  (S),  is  permeated  at  rapidly  following  inter- 
vals by  thin  bundles  of  uriniferous  tubes,  having  a  straight 
course  (A),  which  diminish  in  size  as  they  pass  outwards,  and 
only  become  lost  in  convolutions  (d)  just  beneath  the  surface  of 
the  kidney.  These  groups  of  straight  passages,  whose  calibre 
is  also  variable  (a  t>),  penetrate  the  layer  of  the  convoluted  ca- 
nals in  the  same  manner,  we  might  say,  that  a  board  is  perforated 
by  numerous  pegs  driven  closely  together  into  it. 

These  bundles  of  straight  canals  which  were  previously  seen, 
and  which  are  continuations  of  the  familiar  straight  passages 
of  the  medullary  substance,,  have  been  called  pyramidal  pro- 
cesses (Henle)  or  medullary  rays  (Ludwig).  We  shall  soon 


510 


SECTION    TWENTIETH. 


return  to  the  consideration  of  their  signification.  The  tissue  of 
the  convoluted  uriiiiferous  canals  lying  between  them  may  be 
considered,  although  indeed  only  factitiously,  as  consisting  of 


Fig.  276.  Vertical  section  through  the  renal  cortex  of  the  new-born  child  (semi-diagrammatic). 
AA,  medullary  rays ;  J3,  cortical  substance  proper ;  a,  collective  tube  of  the  medullary  ray ;  6, 
finer  uriniferous  canalicules  of  the  latter ;  c,  convoluted  canalicules  of  the  cortical  substance ;  d, 
their  peripheral  stratum ;  e,  arterial  branch  ;  /,  glomeruli  ;  g,  continuation  of  a  uriniferous  canal 
into  the  Bowman's  capsule  ;  /i,  the  renal  tunic  with  its  lymph-spaces,  t. 


individual  pyramidal  pieces  which  have  their  bases  turned  to- 
wards the  renal  capsules.  These  are  the  cortical  pyramids  of 
Henle. 

Transverse  sections  of  the  cortex  (fig.  277)  show  both  varieties 
of  the  uriniferous  canals ;  those  of  the  medullary  rays  cut  trans- 
versely (a),  those  of  the  ordinary  cortical  substance  (5),  in  all 
possible  forms.  The  connective-tissue  stroma  may  also  be 
readily  recognized  at  the  same  time. 


UKINAEY    ORGANS.  511 

If  the  study  of  the  epithelium  be  renounced,  I  would  here 
recommend  still  another  method  which  became  known  to  me 
through  Billroth.  If  a  portion  of  kidney  be  treated  for  a  very 
short  time  with  boiling  vinegar  it  will,  after  having  been  dried, 
or  hardened  by  means  of  chromic  acid  or  alcohol,  afford  very 


Fig.  277.  Surface  section  through  the  cortical  substance  of  the  kidney  of  the  new-born  child 
(semi-diagrammatic),  a,  Transverse  section  through  the  uriniferous  canalicules  of  the  medullary 
ray  ;  6,  convoluted  canals  of  the  cortical  substance  proper  ;  c,  glomeruli  and  capsules  of  Bowman. 

handsome  views  of  the  glandular  passages  in  the  medulla  and 
cortex. 

The  chemical  method  of  isolation  has  more  recently  assumed 
the  greatest  importance  in  the  investigation  of  the  kidney. 
The  fresh  tissue  (or  also  that  which  has  been  hardened  in  alco- 
hol), treated  with  strong  muriatic  acid  (p.  129),  suffers,  after  a 
series  of  hours,  an  almost  complete  destruction  of  the  connective- 
tissue  interstitial  substance,  while  the  blood-vessels,  and  espe- 
cially the  uriniferous  canals,  remain  completely  intact ;  and  not 
unf  requently  even  their  epithelium  is  almost  entirely  preserved. 
These  canals  may  then  be  isolated  by  very  slightly  shaking  or  a 
gentle  manipulation  with  the  needles,  or,  already  floating  in  the 
fluid,  they  may  be  fished  out  with  a  curved  glass  r<id.  The 
whole  has,  it  is  true,  become  very  frail  and  readily  destructible ; 
nevertheless,  we  may  frequently  succeed  in  tingeing  them 
slightly  with  carmine,  and  mounting  them  very  handsomely  in 
watery  glycerine. 

The  muriatic  acid  may  be  used  in  various  ways  for  this  pur- 
pose. 


512  SECTION   TWENTIETH. 

The  ordinary  commercial  muriatic  acid  has  frequently  been 
diluted  with  water  until  it  ceased  to  fume,  and  the  object  im- 
mersed in  it  from  twelve  to  twenty-four  hours.  Schweigger- 
Seidel  employed  the  officinal,  pure  muriatic  acid  of  the  Prus- 
sian pharmacopoeia  (of  1120  sp.  wt.),  and  allowed  the  pieces  taken 
from  an  animal  killed  about  a  day  previously  to  macerate  in  it 
from  fifteen  to  twenty  hours.  •  Stronger  acid  acts  rapidly,  but  at- 
tacks the  gland-cells  energetically ;  that  which  is  weaker  requires 
more  time.  The  pieces  must  afterwards  be  carefully  washed 
with  distilled  water,  and  a  subsequent  maceration  of  the  same 
for  one  or  more  clays  in  water  will,  for  the  most  part,  essentially 
further  the  isolation.  Boiling  with  this  acid  or  with  alcohol 
containing;  muriatic  acid,  has  also  been  recommended. 

If  the  chemical  isolation  has  been  successfully  accomplished 
(which  is  not  always  the  case,  however),  such  objects  (fig.  274, 
figs.  278-281)  afford  the  circumspect  observer  extremely  im- 
portant information. 

It  is  naturally  impossible,  even  with  the  most  conservative 
manipulation,  to  isolate  a  uriniferous  canal  throughout  its  entire 
course ;  it  is  here,  therefore,  only  a  question  of  obtaining  the 
longest  possible  fragments  and  of  their  combination.  The 
expert  will  obtain  these  in  lengths  of  from  1-2'",  at  least  here 
and  there.  In  consequence  of  the  enormous  length  of  the  canal- 
work  in  question  in  the  kidneys  of  the  larger  creatures,  a  suc- 
cessful result  becomes  much  more  difficult  in  them  than  in  the 
organs  of  the  smallest  mammalia.  The  kidneys  of  the  mole,  the 
bat,  the  marmot,  the  mouse,  rat,  and  Guinea-pig  deserve  to  be 
chiefly  recommended.  As  Prussian  blue  is  preserved  in  the 
acid  macerating  fluid  the  blood-vessels  are  to  be  previously  in- 
jected, a  precautionary  measure  which  is  extremely  important 
for  the  study  of  the  medullary  loops. 

If  the  examination  be  commenced  with  the  medullary  sub- 
stance from  the  apex  of  its  pyramids  one  may  recognize  how  the 
open  canals,  with  their  characteristic  epithelial  covering,  form  a 
number  of  rapidly  following  forked  divisions  (fig.  274  «-<?,  278 
a  I),  and  then,  the  branches  having  become  narrower,  assume  a 
straight  course  and  pass  unchanged  for  long  distances  through 
the  medullary  substance  (fig.  278  c)  until  they  arrive  at  the  ex- 


URINARY    ORGANS. 


513 


ternal  portion  of  the  medulla,  which  is  characterized  by  tuft- 
shaped  blood-vessels  (boundary  layer  of 
Henle).  Between  them  appear,  through- 
out all  the  layers  of  the  pyramids,  the 
much  narrower  loop-shaped  canaliculi 
(d),  which  are  lined  with  flat,  transparent 
cells.  Their  returning  sides,  that  is,  the 
ones  which  again  tend  towards  the  cortex, 
may  show  themselves  to  be  enlarged  and 
filled  with  darker  granular  gland-cells. 

The  open  canals  in  leaving  the  bound- 
ary layer  pass,  for  the  most  part  single, 
more  rarely  by  twos,  into  each  medullary 
ray,  through  which  they  continue  towards 
the  surface  of  the  kidney  (fig.  276,  A). 
The  appropriate  name  of  collective  tubes 
has  been  given  them  (a). 
The   above  -  indicated 
differences   in  the  epi- 
thelium   here    become 
less   distinct.     The   re- 
maining    considerably 
narrower  canals  of  the 
medullary   ray    consist 
of  the  descending  (that 
is,  turned  towards  the 
hilus)   and  the   return- 
ing sides  of  the  loop- 
shaped  canals  (J). 

The  collective  tube, 
having  arrived  nearer 
the  surface  of  the  kid- 
ney, gives  off  more  nu- 
merous branches  (figs. 
280  c,  281  c)  and  termi- 
nates above  in  arched 


Fig.  279.  Looped  ca- 
nalicule  from  a  renal 
pyramid  of  the  new- 
born child,  a  ft,  The  two 
sides ;  c,  another  canali- 
cule  ;  d,  capillary  vessel. 


Fig.  278.  Vertical  section  through  the  medullary  pyramids  of  the  pig's  kindey  (semi  diasrmm- 
matic).  a,  The  trunk  of  a  uriniferous  canal  opening  at  the  apex  of  the  pyramid ;  b  and  c,  its 
system  of  branches  ;  d,  the  loop-shaped  uriniferous  canals  ;  e,  vascular  loops,  and  /,  divisions  of 
the  vasa  recta. 

33 


514 


SECTION    TWENTIETH. 


ramifications  (figs.  280  d,  281  d),  which,  especially  in  the  smaller 
animals,  may  present  a  zigzag  appearance  ("intercalary  por- 
tions "  or  "  connecting  canals  ").  From  them,  but  also  deeper 
from  the  stem  of  the  collective  tube,  rapidly  narrowing  canals 
of  various  forms  arise,  the  descending  sides  of  the  loops  (e), 
whose  entrance  here  from  the  medullary  substance  has  been 
shown  in  other  macerated  preparations. 
d 


Fig.  280.  Vertical  section  from  the  kidney 
Of  the  Guinea-pig  (muriatic  acid  preparation). 
a,  Trunk  of  a  collective  tube  ;  6,  its  branches  ; 
c,  further  division ;  d,  convoluted  canal  (in- 
tercalary portion)  ;  e,  descending  side  of  a  loop- 
shaped  uriniferous  canal ;  /,'  loop  ;  gr,  return- 
ing side ;  and  A,  continuation  into  convoluted 
canals  of  the  cortical  substance. 


Fig.  281.  Vertical  section  from  the  kidney  of 
the  mole  (muriatic  acid  preparation),  c,  Term- 
inal branch  of  the  collective  tube ;  d,  convolut- 
ed portion  of  canal :  e,  descending  side  of  the 
looped  canal ;  /,  loop ;  g  A,  returning  side  and 
continuation  into  the  convoluted  canaliculea 
i;  *,  neck-piece  of  the  latter;  f,  Bowman's 
capsule;  TO,  glomerulus. 


Having  thus  become  acquainted  with  the  one  side  as  an  off- 
shoot or  a  terminal  branch  of  the  open  uriniferous  canals,  the 
question  still  arises,  what  becomes  of  the  other,  the  returning 
side  (figs.  280  and  281  g  g). 


URINARY    ORGANS. 


515 


This,  accompanied  by  the  canalicules  of  the  medullary  ray, 
bends  deeper  or  higher  from  the  group  in  a  lateral  direction 
(figs.  280  A,  281  A),  assumes  another  convoluted  course,  gains  at 
the  same  time  an  increased  diameter  and  a  darker  granular 
epithelium,  and  becomes  an  ordinary  convoluted  uriniferous 
canal  of  the  cortical  substance  proper,  and,  finally,  with  numer- 
ous windings  and  curves,  terminates  as  the  Bowman's  capsule 
of  the  glomerulus  (fig.  281  Jc  I).  We  must  here  pass  over  in 
silence  many  peculiarities  of  a  subordinate  nature. 

We  will  only  mention  one  condition  here,  namely,  that  of  the 
epithelial  lining  of  the  Bowman's  capsule  (fig.  282).  Its  inner  sur- 
face has  a  layer  of  pavement-cells  (g)  of  considerable  size,  which 
may  be  easily  rendered  visible  by  means  of  nitrate  of  silver  (either 
by  simple  immersion  or  by  injecting  from  the  artery).  More 
difficult  of  recognition,  and  in  a  singular  manner  not  permitting 
of  the  impregnation  with  silver,  is  a  layer  of  smaller  and  higher 
cells,  which  cover  the  surface  of 
the  glomerulus  (f).  They  are 
to  be  seen  in  the  frozen  organ 
(Chrzonszczewsky) . 

Not  less  important  for  the  in- 
vestigation of  the  structure  of 
the  kidneys  is  the  injection  of 
their  glandular  canals  from  the 
ureter.  Cold-flowing  mixtures 
are  to  be  used  for  this  purpose. 
The  addition  of  alcohol  is  not 
suitable  for  such  investigations, 
although  also  not  an  absolute 
hindrance,  as  has  been  here  and 
there  asserted.  It  is  most  suit- 
able to  select  a  wateiy  Prussian 
blue  or  carmine,  to  which  gly- 
cerine or  gum-arabic  may  be 
added  (see  p.  186). 

The  varying  pressure  of  the  injecting  syringe  is  less  suitable 
than  the  constant  pressure  of  a  column  of  fluid  or  quicksilver 
(comp.  p.  189),  which  may  be  gradually  increased.  Such  in- 


Fig.  282.  Glomerulus  of  the  «abbit  (dia- 
grammatic), a,  Vas  afferens  ;  ft,  vas  effer- 
ens ;  c,  glomerulus ;  d.  under  portion  of  the 
capsule  (without  epithelium) ;  e,  neck  ;  /, 
epithelium  of  the  glomerulus ;  and  g,  that 
of  the  inner  surface  of  the  capsule  after 
treatment  with  silver. 


516  SECTION   TWENTIETH. 

jections  then  require  many  hours,  and,  notwithstanding  every 
precaution,  not  unfrequently  remain  without  the  desired  result. 
While  the  simply-constructed  kidneys  of  a  frog  or  of  a  coluber 
natrix  may  be  injected  with  facility,  the  attempts  miscarry  in 
small  mammalial  animals  from  speedy  extravasations  into  the 
venous  system.  Only  embryonic  kidneys,  in  consequence  of 
the  slightly  developed  medullary  substance;  occasionally  afford 
the  cautious  experimenter  a  successful  result.  As  a  rule,  the 
organs  of  the  dog,  the  sheep,  the  calf,  and  the  pig  are  to 
be  used,  and  in  as  fresh  a  condition  as  possible.  The  pig's 
kidney  may  be  injected  under  the  pressure  of  a  quicksilver 
column  of  50-100  millimetres  and  more. 

One  succeeds  with  comparative  facility,  after  filling  the 
open  canals  of  the  medulla  (fig.  278),  in  forcing  the  injection 
mass  to  the  end  of  the  medullary  rays  and  their  systems 
of  branches.  The  descending  sides  of  the  looped  canals,  which 
are  turned  towards  the  hilus,  may  also  be  filled  with  relative 
facility,  and  are  characterized  by  their  smaller  diameter.  The 
colored  fluid  passes  with  greater  difficulty  through  the  loop 
itself,  and  into  the  returning  side.  The  most  rarely — and  it  is 
appreciable  from  the  nature  of  the  contents  and  the  convolu- 
tions— does  one  succeed  in  forcing  the  injection  mass  through 
the  convoluted  canalicules  of  the  cortex  into  the  capsules  of 
Bowman.  Numerous  successful  results  have,  however,  been 
more  recently  obtained,  and  thus  the  inferences  presented  by 
maceration  confirmed  (Ludwig-Zawarykin,  Kollmann,  Chrzon- 
szczewsky,  Hertz,  Frey,  and  others. 

Our  diagram,  fig.  283  (which  contains  the  sketch  of  two  such 
courses  of  the  injection  from  the  medullary  canal  (i)  to  the 
right  and  left  Bowman's  capsules),  may  represent  to  the 
reader  the  results  of  the  injection,  of  which  only  the  chief 
points  have  been  described. 

To  recapitulate,  let  iis  again  follow  the  course  which  the 
secretion  must  take  from  the  glomerulus.  Surrounded  by  the 
capsule  of  Bowman  (a),'  it  passes  over  into  the  convoluted  uri- 
niferous  canalicule  (&),  which,  after  its  convolutions,  assumes  a 
straight  course  towards  the  apex  of  the  papilla  (c).  Changing 
its  epithelium,  it  passes,  more  or  less  downwards,  through  the 


UKLtfAKY    OKGANS. 


517 


and 


returns 


papilla,  bends  around  in  a  loop-like  manner, 
with  the  other  side  to  the 
cortex  (d).  This  side,  later 
or  earlier,  alters  its  character, 
becomes  broader  and  more 
convoluted  (<?),  and  enters, 
sooner  or  later,  in  connection 
with  other  similarly-constitu- 
ted passages,  into  the  collec- 
tive tube  (f)y  which,  uniting 
with  others  at  an  acute  angle 
(g  A),  finally  pours  out  the 
urine  at  the  apex  of  the  pa- 
pilla (i). 

The  new  method,  the  self- 
injection  of  the  living  animal, 
with  which  Chrzonszczewsky 
has  made  us  acquainted,  has 
already  been  mentioned  in  a 
previous  section  of  this  book 
(p.  187).  Although  the  ap- 
pearances thus  obtained  are 
variable  and  not  always  com- 
prehensible, repetitions  of  the 
experiment  with  injections  of 
a  solution  of  carmine  into 
the  jugular  of  the  rabbit 
have  nevertheless  afforded 
me  good  results. 

We  have  still  to  mention 
the  connective-tissue  stroma, 
as  well  as  the  blood  and 
lymph  passages  of  our  or- 
gan. 

The  course  of  the  vessels  in 
the  kidney  has  been  so  fre- 

Fig.  283.  Diagrammatic  representation  of  the  arrangement  of  the  uriniferotis  canals  (using  the 
pig's  kidney),  a,  Bowman's  capsules;  &,  convoluted  uriniferous  canal  and  returning  side  of  the 
loop,  c;  d,  descending  side;  e,  convoluted  tube;  /,  collective  tubes,  uniting  into  a  larger,  open 
uriniferous  canal  (g),  which  is  joined  by  others  to  form  the  canal  A;  t,  trunk  which  opens  at  the 
apex  of  the  papilla. 


518  SECTION   TWENTIETH. 

quently  described  (in  an  especially  excellent  manner  by  Hyrtl), 
that  we  may  here  limit  ourselves  to  the  most  necessary  state- 
ments. The  branches  formed  by  the  division  of  the  renal  artery 
and  vein  pass  through  the  medullary  substance  between  the  sev- 
eral Malpighian  pyramids.  At  the  basis  of  the  latter,  bow-like 
arrangements  of  both  varieties  of  vessels  are  noticed.  From  the 
arterial  arches  arise  then,  in  the  form  of  branches,  the  coil-sup- 
porting arteries  of  the  cortical  substance,  which  keep  in  the  axial 
part  of  a  portion  of  cortex  (cortical  pyramid)  bounded  by  two 
medullary  rays,  and  towards  the  periphery  give  off  the  afferent 
vessels  of  the  glomerulus  (fig.  276  ef;  fig.  283  I). 

This,  the  vas  afferens,  undergoes,  in  man,  further  acute-angled 
divisions  within  the  coil-shaped  convolutions  (fig.  273  £),  and 


Fig.  284.  From  the  kidney  of  the  pig  (semi-diagrammatic),  a,  arterial  branch ;  6.  afferent  ves- 
sel of  the  glomerulus,  c ;  d,  vas  efferens ;  e,  breaking  up  of  the  same  into  the  straight  capillary 
plexus  of  the  medullary  ray ;  /,  rounded  plexus  of  the  convoluted  canals,  i ;  fir,  commencement  of 
the  venous  branch. 

forms,  after  the  convolutions,  by  the  reunion  of  the  latter 
branches,  the  efferent  vessel,  the  vas  efferens  (fig.  273  c  /  284  d). 
The  latter  then  disappear  in  a  capillary  network  with  elongated 
meshes  which  encircles  the  straight  uriniferous  canals  (fig.  284 
e).  From  the  periphery  of  the  latter  are  first  formed  those  ca- 
pillary tubes  (f)  which  encompass  with,  rounded  meshes  the 
convoluted  uriniferous  canalicules  (i)  of  the  cortical  substance 
proper. 

The  most  superficial  stratum  of  the  cortical  substance,  which 
is  free  from  vascular  coils,  receives  its  capillaries  substantially 
from  the  efferent  vessels  of  the  superficial  glomeruli ;  much 


URINARY    ORGANS.  519 

more  sparsely  (and  certainly  not  in  all  mammalial  animals)  from 
several  of  the  terminal  branches  of  the  glomerular  arteries, 
which  pass  directly  and  immediately  forward  to  this  peripheral 
layer. 

Venous  roots  appear  close  beneath  the  capsule  in  the  form  of 
star-shaped  figures  ;  other  venous  roots  arise  deeper  in  the  con- 
nective tissue.  Generally  coalescing  into  larger  trunks,  both 
varieties  of  venous  branches  empty  at  the  boundary  of  the  cor- 
tex and  medulla  into  the  arched  vessels. 

The  long,  rectilinear  vascular  tufts,  which  appear  between 
the  uriniferous  canicules  in  the  medullary  substance  (its  boun- 
dary layer),  then  extend  downward  and 
either  pass  over  into  each  other  in  a 
loop-like  manner,  or  form  a  delicate 
network  around  the  apertures  of  the 
uriniferous  canals  at  the  apex  of  the 
pyramid,  and  are  called  vasa  recta  (fig. 
276  e  f).  Between  these  there  also 
appears  a  capillary  network  of  finer 
tubes. 

-, .  . .  /,  .     .  Fig.  285.    From  the  boundary 

A     great     diversity     OI      Opinion    pre-       layer   of  the  human  kidney,     a, 

.,  .  ,  ../,-.  Arterial  trunk ;    &,   one  branch, 

VailS     Concerning     the     Origin     Ol     these       and  e  another  which  furnishes  the 

vasa  afferentia   of    two  glomera- 

VaSa  recta.  ll  at  c  and  d  ,•  /,  a  third  branch 

(arteriola  recta),  with  its  division 

According    tO    OUr    Observation,    they       into  rectilinear  capillaries  of  the 
°  i       •       i  medullary  substance,  g. 

nave  essentially,  it  not  also  exclusively, 

a  venous  character,  as  they  are  formed  from  continuations  from 
the  capillary  network  of  the  medullary  rays.  The  vasa  effe- 
rentia  of  deeply  situated  glomeruli  are  joined  to  them  as  arterial 
supplies.  Quite  unimportant,  finafly,  are  the  arterial  branches 
(arteriolse  rectae),  which,  even  before  the  giving  off  of  the  glome- 
ruli, have  left  the  coil-bearing  artery,  and  become  buried  in  the 
rectilinear  vascular  district  (fig.  285  f). 

As  we  have  above  remarked,  the  larger  trunks  frequent- 
ly divide,  in  a  tuft  or  tassel-like  manner,  into  these  vasa 
recta. 

Exactly  the  same  appearance  is,  in  general,  also  presented  by 
the  meeting  of  the  returning  straight  vessels.  Their  insertion 
takes  place  in  the  arched  veins,  which  we  have  become  ac- 


520  SECTION    TWENTIETH. 

quainted  with  above,  as  occurring  at  the  margin  of  the  cortex 
and  medulla. 

The  ascertaining  of  such  extremely  complicated  conditions 
premises,  naturally,  extensive  studies  of  injections  and  very 
careful  examinations  of  the  preparations. 

Notwithstanding  the  facility  with  which  the  kidney  may  be 
injected  by  the  arteria  renalis  (so  that  it  constitutes  a  good  ex- 
ercise for  beginners),  and  however  little  it  can  be  called  a 
display  of  skill  to  accomplish  an  extensive  injection  of  the  me- 
dullary substance,  the  question  as  to  the  finer  vessels  of  the  organ 
requires  entire  series  of  other  injections.  We  would  advise,  first, 
the  very  early  discontinuance  (at  various  stages)  of  the  injection 
by  the  artery,  as  soon  as  some  coloring  matter  has  reached  the 
cortex.  We  would  then  recommend  other,  somewhat  longer 
continued  arterial  injections,  with  which  the  medullary  rays,  but 
not  the  capillaries  of  the  portions  of  cortex  lying  between 
them,  are  injected. 

Other  instructive  preparations  are  afforded  by  the  injection 
by  the  vein,  which  is  likewise  to  be  discontinued  at  various 
stages.  Iilven  an  extensive  venous  injection  usually  clogs  at  the 
glomerulus.  Thin  fluid  masses  may  be  injected  into  them,  how- 
ever, even  by  the  vein. 

The  double  injection  is,  finally,  very  instructive.  It  should 
be  commenced  by  the  vein,  and  be  continued  sometimes  more, 
sometimes  less  by  the  arterial  or  the  venous  side.  Greater 
practice  is  here  necessary.  If  a  gelatine  mass  has  been  selected 
for  the  complete  filling  of  the  veins,  it  is  advisable,  for  the  re- 
cognition of  the  boundary  district  of  both  varieties  of  vessels, 
to  undertake  the  subsequent  injection  of  the  arteries  with  cold- 
flowing  masses. 

We  would  chiefly  recommend  the  kidneys  of  dogs,  cats,  and 
rabbits.  Of  larger  animals,  those  of  the  pig  and  sheep  are  to 
be  used.  If  the  system  of  uriniferous  canals  has  been  filled 
with  Prussian  blue,  the  carmine  mass  and  the  transparent  yel- 
low of  Thiersch  (p.  182)  is  to  be  selected  for  the  injection  of  the 
blood-vessels.  Human  kidneys,  even  from  bodies  which  are  110 
longer  fresh,  frequently  afford  good  results.  Injections  of  the  or- 
gan in  Bright's  disease  are  also  usually  more  or  less  successful. 


URINARY    ORGANS.  521 

A  connective-tissue  stroma  is  met  with  as  the  framework  of 
the  kidney.  It  consists,  in  the  cortical  substance,  of  a  but  very 
little  developed  connected  septal  system  of  connective-tissue 
cells  and  homogeneous  or  striated  interstitial  substance.  It  ap- 
pears somewhat  thicker  on  the  adventitia  of  the  larger  vessels 
and  the  capsules  of  Bowman,  and,  metamorphosed  at  the  sur- 
face of  the  organ  into  a  connective  tissue  with  numerous  spaces, 
is  continued  into  the  renal  capsules.  This  connective-tissue 
stroma  becomes  somewhat  firmer  in  the  medullary  rays;  it 
reaches  its  greatest,  although  absolutely  slight  development  in 
the  medullary  substance  (fig.  275  e).  Thin  sections  from  the 
organ  which  has  been  hardened  in  alcohol  or  chromic  acid  af- 
ford the  very  best  views  when  brushed  or  tinged  wTith  carmine 
The  star  shaped  connective-tissue  cells  may  be  beautifully  iso- 
lated by  macerating  in  muriatic  acid  (Schweigger-Seidel). 

The  attempts  to  inject  the  lymphatics  of  the  kidney  by  means 
of  the  puncturing  method  have  been,  for  the  most  part,  unsuc- 
cessful. It  succeeds  best  by  the  swollen  vessels  of  organs  (of 
the  dog)  which  have  been  rendered  oedematous  by  ligating  the 
ureter.  The  parenchymatous  lymphatics  occupy  the  interstices 
of  the  connective  tissue  (fig.  276  *),  abounding  in  spaces,  which 
lies  beneath  the  capsule,  and  pass  inwards  from  here  through 
the  spaces  of  the  connective-tissue  stroma,  between  the  uri- 
niferous  canals,  around  the  capsules  of  Bowman  and  the  finer 
blood-vessels.  While  the  intercommunication  of  these  lym- 
phatics in  the  cortical  tissue  is  very  free,  it  is  only  subsequently 
that  the  narrower  spaces  of  the  medullary  rays,  and  finally  the 
passages  of  the  medullary  substance  itself,  become  filled.  The 
whole,  moreover,  reminds  one  strongly  of  the  lymphatics  of  the 
testicle  (see  below). 

Through  the  industry  of  competent  investigators  we  have 
become  more  intimately  acquainted  with  the  numerous  patho- 
logical changes  of  the  renal  tissues.  Here,  also,  the  predomi- 
nant participation  of  the  connective-tissue  frame-work  in  the 
morbid  textures  was  for  a  long  time  firmly  maintained,  and  the 
new  formations  were  also  said  to  take  their  origin  from  its  cells, 
while,  in  this  regard,  the  structureless  membrane  of  the  glandu- 
lar passages  was  considered  as  playing  a  subordinate  role.  The 


522  SECTION    TWENTIETH. 

gland-cells  themselves  were  capable,  indeed,  of  swelling,  the 
production  of  granular  contents,  of  increase,  as  well  as  of  degen- 
eration (especially  the  fatty),  and  of  decay  (and  these  occurrences 
are  yery  frequent),  but  corresponding  to  their  epithelial  nature, 
did  not  pass  over  into  other  tissue  elements, — all  acceptations 
which  properly  meet  with  renewed  doubts  at  the  present  day. 

Increase  of  the  connective-tissue  framework  substance,  partly 
local,  partly  diffused,  is  frequently  met  with  in  the  kidney. 
After  the  application  of  the  methods  already  mentioned,  the 
connective  tissue  appears  sometimes  homogeneous  and  compact, 
sometimes  split  up  into  fibrillae  with  its  cells  usually  more  dis- 
tinct. The  related  substance  of  the  membrana  propria,  espe- 
cially in  the  capsule  of  Bowman,  also  undergoes  thickening, 
now  and  then  with  a  stratified  appearance.  "Whether  the  cell- 
like  bodies  which  may  be  rendered  visible  under  such  conditions 
are  actually  connective-tissue  cells  belonging  to  the  capsular 
membrane,  we  will  leave  undecided.  From  these  connective- 
tissue  cells  commence  additional  processes  of  multiplication, 
which  may  lead,  in  part,  to  the  formation  of  new  connective- 
tissue  corpuscles,  in  part  to  the  production  of  spherical  cells, 
similar  to  the  elements  of  the  lymph  and  pus,  whereby,  how- 
ever, the  emigration  of  the  coloress  blood-corpuscles  will  also 
play  its  part.  The  pus  of  the  renal  tissue  also  consists  of  such 
cells.  A  similar  process  of  proliferation,  but  accompanied  by 
shrivelling  and  fatty  degeneration,  is  produced  by  tuberculosis 
of  the  kidney,  while  miliary  tubercle  here  also  frequently  takes 
its  origin  from  the  sheaths  of  the  arteries.  Other,  and  especially 
carcinomatous  new  formations  are  also  said  to  take  their  origin 
from  this  connective  tissue,  ^his  has  recently  been  denied, 
however,  so  far  as  the  cells  of  the  former  are  concerned,  as  they 
are  thought  to  originate  from  the  glandular  epithelium  (Wal- 
deyer). 

Brief  mention  may  here  be  made  of  the  deposits  of  fatty  and 
pigment  molecules  as  well  as  of  the  amyloid  degeneration. 
Even  in  the  normal  kidney  one  may  meet  with  a  few  molecules 
of  fat  in  the  fine  granular  contents  of  the  glandular  epithelium ; 
the  number  of  the  same  is  occasionally  not  inconsiderable. 
Large  collections  of  them,  which  may  produce  a  fatty  degenera- 


UKIttAKY    ORGANS.  523 

tion  of  these  cells  leading  to  their  destruction,  are,  in  pathologi- 
cal conditions,  of  extraordinarily  frequent  occurrence.  These 
fat-granules  also  appear  within  the  trabeculse  and  the  connec- 
tive-tissue corpuscles  of  the  connective-tissue  framework.  Grad- 
ually flowing  together  in  the  connective-tissue  cells,  they  may 
lead  to  the  formation  of  globular  fat-cells. 

Eemarkable  pigmentations  of  the  kidneys  (preponderating, 
however,  in  the  gland-cells)  may  be  met  with  in  persons  who 
have  been  destroyed  by  an  obstruction  of  the  biliary  ducts.  We 
have  already  (p.  470)  mentioned  the  changes  which  occur  in  the 
liver-cells  with  such  a  retention  of  the  bile.  Such  kidneys  pre- 
sent an  olive-green  color.  Variously  tinged  epithelium  is  seen 
in  the  uriniferous  canals  of  the  medullary  substance,  likewise 
epithelium  with  variously  colored  masses  of  pigment  in  the  cell- 
bodies.  In  cases  of  high  degree  the  uriniferous  canals  are  ob- 
served to  be  filled  with  lumps  of  hard,  brittle  black  substances* 
A  similar  but  blacker  pigmentation  is  also  met  with  in  the  con- 
voluted uriniferous  canals  of  the  cortex,  as  well  as  in  the  cap- 
sules of  Bowman,  that  is,  in  the  epithelium  of  the  glomerulus. 

Melansemia,  the  passage  of  pigmentated  cells  and  flakes  from 
the  spleen  in  malignant  intermittents  (p.  485),  causes  embolia 
in  the  renal  vessels  by  means  of  the  structures  mentioned.  The 
masses  of  pigment  are  found  in  the  vessels  of  the  glomerulus, 
the  capillaries  of  the  cortex,  more  rarely  in  those  of  the  me- 
dulla. A  few  such  pigment  aggregations  may  be  met  with 
even  in  the  uriniferous  canals. 

The  participation  of  the  gland-cells  is  probably  somewhat 
greater  in  the  not  unfrequent  amyloid  degenerations  of  the 
kidneys.  They  become  transformed  into  the  characteristic 
flake-like  bodies,  similar  to  those  which  we  have  mentioned 
above  (p.  4T5)  at  the  equivalent  degeneration  of  the  liver.  The 
seat  of  the  degeneration  is  predominantly  in  the  vascular  walls, 
especially  those  of  the  glomerulus  (vas  afferens,  convoluted 
canals,  and  efferent  vessels).  The  mernbrana  propria  may  also 
undergo  the  process  of  degeneration. 

An  interesting  succession  of  the  just-mentioned  metamor- 
phoses of  these  several  elements — the  glandular  and  the  con- 
nective-tissue elements,  together  with  the  vascular — is  shown  by 


524  SECTION   TWENTIETH. 

the  process  called  "  Bright's  disease."  This  commences  with 
an  increased  inflammatory  congestion  and  swollen,  granular 
gland-cells,  leading  to  an  extensive  destruction  of  the  gland- 
cells  of  the  organ  as  well  as  of  its  blood-vessels,  with  which  is 
also  associated  a  considerable  increase  of  the  connective-tissue 
frame-work  substance,  and  a  further  metamorphosis  of  the 
glandular  tissue. 

At  the  commencement  periods,  especially  of  severe  and 
rapidly  progressing  cases,  one  notices  in  the  cortical  substance, 
where  these  pathological  processes  first  take  place,  a  consider- 
able repletion  of  the  finer  vessels  with  blood,  and  somewhat 
cloudy,  granular  gland-cells.  The  vascular  coils  appear  more 
distinct,  small  extravasations  from  ruptured  vessels  are  frequent, 
and  glassy  cylindrical  masses  of  albuminous  substances  begin 
to  appear  in  the  straight  uriniferous  canals.  These  "fibrin 
cylinders"  (which  are  to  be  distinctly  recognized  in  hardened 
kidneys  as  masses  filling  the  glandular  canals)  sometimes 
present  more  of  an  appearance  of  pure  fibrin,  sometimes  they 
appear  to  be  more  impregnated  with  a  few  blood-corpuscles 
and  separated  gland-cells.  At  a  later  period  the  quantity  of 
blood  contained  in  the  cortex  of  the  kidney  diminishes ;  injec- 
tions of  the  organ,  which  is  frequently  increased  in  volume, 
now  succeed  with  greater  difficulty.  A  fatty  degeneration 
takes  place  extensively  through  the  gland-cells,  and  even  the 
fibrin  cylinders  frequently  contain  such  fragments  of  cells  and 
free  granules  of  fat.  Other  gland-cells  shrivel,  without  present- 
ing these  fat-molecules.  In  well  -  hardened  preparations  the 
connective- tissue  framework  substance  is,  for  the  most  part, 
found  to  be  increasing  by  proliferation.  If  these  cylinders  are 
not  washed  away  by  the  current  of  the  urine  (in  which  case 
they  appear  as  urinary  constituents),  the  obstructed  uriniferous 
canals  become  widened  and  sinuous,  and  in  this  way  may  give 
origin  to  the  formation  of  cysts.  If  the  process  continues,  the 
glandular  canals  are  found  to  be  deprived  of  their  epithelium, 
filled  with  detritus,  and,  in  part,  collapsed  and  gradually  dis- 
appearing in  the  increasing  connective  tissue.  Concentric 
depositions  of  connective  tissue  also  occur  around  the  shrink- 
ing capsules  of  Bowman.  In  this  manner  are  formed,  here  and 


UKINARY    ORGANS.  525 

there,  these  metamorphosed  connective-tissue  places  in  kidneys 
which  are  decreasing  in  volume.  Between  them  remain  portions 
of  glandular  tissue,  widened  canals  filled  with  granular  masses, 
etc.  These  are  the  so-called  "granulations"  of  pathological 
anatomy. 

The  structural  changes  in  question  can  only  be  inadequately 
and  unsatisfactorily  followed  in  the  fresh  organ,  although  such 
examinations  should  always  be  made,  especially  on  account  of 
the  metamorphoses  of  the  cells.  Hardened  kidneys  must  serve 
for  further  investigations.  This  procedure  may  present  some 
difficulty  if  the  softness  be  extreme.  The  object  will  be  ob- 
tained after  a  time,  however,  especially  if  the  pieces  immersed 
are  not  too  large  and  a  certain  accuracy  be  observed.  The 
injection  should,  so  far  as  possible,  always  precede  the  immer- 
sion ;  in  many  processes,  such  as  the  formation  of  tubercles, 
amyloid  degeneration,  and  Bright's  disease,  the  microscopical 
preparations  frequently  gain  thereby  a  surprising  intelligibility. 
Tingeing  with  carmine  and  with  aniline  blue  also  deserves  to  be 
urgently  recommended  to  the  physician  for  these  cases.  Where 
more  considerable  connective-tissue  new  formations  are  con- 
cerned, the  preparation  is  to  be  boiled  in  vinegar,  and  then 
immersed  either  in  alcohol  or  in  chromic  acid.  With  the 
latter  treatment,  especially,  many  things  become  very  hand- 
some. 

Several  extensive  deposits  in  the  renal  canaliculi,  originating 
in  the  urinary  constituents,  are  also  to  be  mentioned  here. 
The  so-called  uric  acid  infarction,  which  occurs  in  infants  in  the 
first  days  after  birth,  is  a  common  occurrence.  A  yellowish, 
somewhat  red  substance  fills,  in  streaks,  the  open  uriniferous 
canals  of  the  pyramids,  and  may  be  readily  pressed  from  their 
openings  with  the  fingers.  The  microscope  shows,  mingled 
with  glandular  epithelium,  a  sometimes  homogeneous,  some- 
times coarse  granular  mass  of  uric  acid  salts,  from  which  the 
characteristic  uric  acid  crystals  may  be  separated  by  means  of  a 
drop  of  acetic  acid.  The  altered  assimilation  which  the  pul- 
monary respiration  induces  in  the  body  of  the  new-born  is 
probably  the  cause  of  this  condition,  which  is  not  of  itself 
important.  Not  unfrequently  such  masses  also  appear  in  older 


526  SECTION   TWENTIETH. 

persons,  and  may  become  united  to  concretions  of  uric  acid 
salts.  They  are  met  with,  for  example,  in  Bright's  disease. 

Molecules  of  the  carbonate  of  lime,  as  dark  granular  masses, 
may,  especially  in  advanced  age,  obstruct  the  loop-shaped  urini- 
f erous  canals  (lime  infarction).  They  dissolve  with  effervescence 
by  the  addition  of  acetic  acid  under  the  microscope. 

Kidneys  injected  with  transparent  masses  tinged  with  car- 
mine, and  deprived  of  their  water  by  means  of  absolute  alcohol, 
afford  handsome  preparations  for  a  collection  when  mounted  in 
Canada  balsam.  Other  preparations  are  to  be  preserved  in  the 
customary  manner  with  glycerine.  Concerning  the  methods  of 
examining  the  efferent  portion  of  the  urinary  apparatus,  the 
ureters,  bladder,  urethra,  etc.,  a  few  remarks  may  suffice. 

The  calices  and  pelvis  of  the  kidney,  the  ureters,  and  the 
bladder  scarcely  require  discussion,  as  the  methods  of  investigating 
their  constituent  layers  are  sufficiently  well  known  to  the  reader. 
The  stratified  epithelium  of  these  parts  presents  numerous  and 
peculiar  forms,  with  which  it  is  necessary  to  be  acquainted  in 
order  to  avoid  embarrassment  in  examining  the  urine.  The 
most  superficial  layer  of  the  epithelium  of  the  bladder  (fig.  286 
c)  shows  large,  more  flattened  cells  with  depressions  on  the 
under  surface,  the  one  turned  towards  the  next  following  layer 
of  cells.  The  arched  ends  of  the  cylindrical  cells  of  the  follow- 
ing layer  fit  into  these  cavities ;  nevertheless,  the  cells  of  the 
deepest  of  these  two  layers  are  extremely  irregular  in  form. 
A  similar  condition  is  also  shown  by  the  ureters  and  the  pelvis 
of  the  kidney.  The  cells  of  the  deepest  layer  appear  more 
rounded. 

Of  greater  importance  for  the  practical  physician  is  the 
chemical  and  microscopical  examination  of  the  urine,  of  which, 
however,  we  can  here  only  consider  the  latter. 

Fresh  normal  urine  presents  a  clear  fluid  which  holds  its 
numerous  organic  and  inorganic  matters  in  watery  solution, 
and  contains  but  few  elementary  constituents  from  the  mucous 
membrane  of  the  urinary  passages.  The  latter,  pavement  epi- 
thelium and  mucous  corpuscles,  usually  sink  to  the  bottom  of 
the  vessel  as  a  light  cloud.  A  more  abundant  admixture  of 
tissue  elements  may  appear  in  the  urine  as  a  result  of  patho- 


UKINAKY    ORGANS. 


527 


logical  conditions  of  the  urinary  apparatus,  as  well  as  of  the 
efferent  passages.  They  may  cause  cloudiness  and  changes  of 
color  in  the  fluid  just  evacuated,  which,  after  standing,  deposits 
sediments.  Among  these  are  to  be  enumerated  the  pavement- 
shaped  epithelial  cells  of  the  bladder,  ureters,  and  pelvis  of  the 
kidney,  pus  and  mucous  corpuscles,  blood-cells,  gland-cells  of 
the  uriniferous  canals,  and  so-called  exudation  cylinders  of  the 
latter  (fig.  286).  To  these  may  also  be  added  parasitical  struc- 
tures. 

Kearly  all  these  elements  have  been  already  mentioned.  Pus 
and  mucous  cells  (a)  usually 
occur  in  considerable  numbers 
in  the  urine  in  catarrh  of  the 
bladder;  at  the  later  periods 
only  with  a  very  scanty  ad- 
mixture of  pavement  epitheli- 
um (c).  At  the  commence- 
ment, the  latter  cells  are  more 
abundant,  and  just  in  the  first 
periods  larger  metamorphosed 
epithelial  cells  are  met  with, 
which  present,  together  with 
their  nucleus,  a  number  of  these 
pus  corpuscles  in  the  cell-body. 
So  that  even  here  the  epithe- 
lial origin  of  these  structures  has  been  accepted,  as  has  already 
been  stated  concerning  other  mucous  membranes,  under  similar 
processes.  Blood-corpuscles  (d)  appear  spherically  distended 
in  the  thin  fluid  medium  of  the  urine  ;  gland-cells  (5),  washed 
out  of  the  uriniferous  canals,  present  various  appearances.  - 

We  have  already,  in  sketching  the  Morbus  Brightii,  men- 
tioned the  fibrin  or  exudation  cylinders  (&*i)  characteristic  of 
this  disease.  In  the  rapidly  progressing  form  of  the  disease 
the  urine  is  usually  at  first  bloody.  It  deposits  a  sediment  in 
which  appears,  together  with  swollen  blood-cells,  mucous  and 
pus  corpuscles  as  well  as  epithelium  from  the  pelvis  of  the  kid- 
ney, the  ureters,  and  bladder  (<?),  homogeneous  fibrin  cylinders 
enclosing  (sometimes  numerous,  sometimes  scanty)  blood-cells 


Fig.  286.  Organized  constituents  of  the  urine. 
a,  mucous-  and  pus  corpuscles ;   b,  gland-cells  of 


V8ri<ma 


528  SECTION    TWENTIETH. 

(e).  These  occasionally  contain  crystals  of  uric  acid  or  oxalate 
of  lime  (f).  At  a  later  perjod  these  exudation  cylinders  no 
longer  contain  any  blood-cells,  but,  on  the  contrary,  gland-cells 
of  the  uriiiiferous  canalicules  or  their  remains  (h  g).  If  the 
epithelium  of  the  passages  has  been  entirely  destroyed,  one  may 
meet  with  completely  hyaline,  homogeneous  exudation  cylin- 
ders (i).  In  the  slowly  progressing  form  of  the  disease  with 
which  we  are  occupied,  this  admixture  of  blood-corpuscles  is 
wanting.  Mucous  corpuscles  and  gland-cells  of  the  uriniferous 
canals  (b)  appear,  and  likewise,  varying  exceedingly  in  their 
characteristics,  the  fibrinous  coagula.  They  are  at  first  covered 
by  the  gland-cells,  if  the  exudation  has  taken  place  in  urinifer- 
ous canals  which  are  still  uninjured.  Such  a  covering  of  cells 
may  also  be  met  with  on  these  exudation  cylinders,  even  in 
later  stages,  if  the  latter  have  been  formed  in  passages  which, 
up  to  that  time,  have  remained  intact.  If,  on  the  contrary,  the 
fibrinous  effusion  has  taken  place  in  canals  which  have  already 
lost  their  epithelium,  pure  fibrin  cylinders,  or  those  containing 
only  a  few  fat-granules  may  appear.  If  rapidly  expelled,  they 
are  pale ;  after  remaining  for  a  longer  time  in  the  uriniferous  ca- 
nals they  become  darker  contoured  and  more  yellow,  and  do  not 
rapidly  become  pale  on  the  application  of  acetic  acid.  If  a 
more  considerable  fatty  degeneration  of  the  gland-cells  has 
taken  place,  such  cells,  their  remains,  or  fat-molecules  may 
occur  on  or  in  the  cylinder  (f  g  h}.  Shrivelled  cells  may  also 
show  themselves  in  the  fibrinous  coagulum,  and  even  one  and 
the  same  exudation  cylinder  may  appear  different  in  its  various 
portions. 

The  quantity  of  the  fibrinous  coagula,  affording  a  measure 
of  the  extension  of  the  process  in  the  kidney,  is  extremely  vari- 
able. These  exudation  cylinders  in  the  urine  generally  form 
an  expression  of  the  renal  changes  ;  but  not  an  accurate  one,  as 
the  degeneration  may  be  met  with  in  different  stages  in  various 
portions  of  one  and  the  same  kidney  ;  furthermore  relapses,  that 
is,  a  local  recommencement  of  the  process,  may  occur  (Frerichs). 
Further  remarks  concerning  the  methods  of  investigation  are 
unnecessary. 

Among  the  vegetable  parasites  which  occur  in  the  freshly- 


UKINATtY    ORGANS.  529 

evacuated  urine  may  be  mentioned  the  sarcina,  with  which  we 
have  become  acquainted  from  the  contents  of  the  stomach  (p. 
433).  The  urine  may  receive  casual  admixtures  from  the  se- 
men, as  well  as  from  other  secretory  productions  of  the  male 
and  female  genital  mucous  membranes. 

Our  fluid  much  more  frequently  forms  sediments  from  amor- 
phous and  crystalline  precipitates  of  the  organic  and  inorganic 
constituents  dissolved  in  it.  Among  these  are  to  be  enumerated 
in  the  first  line,  as  the  most  extensive,  the  precipitates  of  uric 
acid,  uric  acid  salts,  oxalate  of  lime,  and  the  ammonio-phosphate 
of  magnesia.  With  these  are  associated  other  rarer  forms. 

These  precipitates,  to  which  allusion  is  here  made  only  in  so 
far  as  their  forms  are  concerned,  are  caused  in  part  by  the  phe- 
nomena of  decomposition  taking  place  in  the  evacuated  urine, 
the  acid  and  alkaline  fermentation,  and  are  therefore  constant 
occurrences,  in  part  depending  on  increased  concentration  and 
altered  composition,  and  are  therefore  isolated,  and  frequently 
pathological  occurrences. 

All  strongly-concentrated  human  urine  deposits,  on  cooling,  a 
finely  granular  yellow  or  brick-colored  sediment,  which  shows, 
by  microscopical  analysis,  small,  dark-contoured  yellowish 
molecules  which  appear  in  irregular  groups  and  aggregations, 
and  in  part  united  in  dendritic  figures  (fig.  287).  This  is  the 
urate  of  soda,  which  is  soluble  on  warming.  It  was  formerly 
erroneously  regarded  as  a  combination  of  uric  acid  with  ammo- 
nia. The  figure  mentioned  shows  in  its  -lower  portion  such 
precipitates  of  the  uric  acid  salt  in  question.  In  the  upper  por- 
tion we  perceive  developed  crystals  which  come  from  urine 
which  had  been  evacuated  for  a  longer  time,  and  in  which  the 
acid  fermentation  had  passed  off  and  the  alkaline  had  com- 
menced. Several  crystals  of  the  oxalate  of  lime  appear  among 
the  molecular  sediments. 

The  uric  acid  soda  salt  also  occurs  in  gouty  concretions. 

Urine  which  has  been  exposed  to  the  atmosphere  for  some 
time  after  its  evacuation  undergoes  at  first,  for  several  days 
(occasionally  weeks),  an  acid  fermentation  whereby  lactic  and 
acetic  acids  are  formed  and  the  acid  reaction  increases.  This 
fermentative  process  usually  commences  rapidly  in  febrile  dis- 
34 


530 


SECTION    TWENTIETH. 


eases.  In  consequence  of  the  same,  the  uric  acid  salt  (urate  of 
soda)  becomes  decomposed,  and  the  uric  acid,  which  is  difficult 
of  solution,  is  separated  and  forms  a  reddish  sediment. 


Fig.  287.  Crystalline  and  amorphous  precipitate  of  the  urate  of  soda. 

Our  fig.  288  shows  the  crystals  of  the  same  which  are  thereby 
formed.  One  usually  recognizes  rhomboidal  tablets  with 
rounded,  obtuse  angles,  and  colored  by  the  urinary  pigment,  as 

represented  below  and  to  the 
right  of  the  figure.  They  have 
received  the  name  of  the  "  whet- 
stone form  "  ("  Wetzsteinf orm  "). 
By  their  union  are  formed  the 
druses  which  are  shown  at  the 
upper  half  of  the  right  side. 
Viewed  from  the  side,  these 
"  whet-stones "  frequently  pre- 
sent cask-shaped  figures.  When 
slowly  precipitated,  uric  acid  (fig, 
288  to  the  left)  may  form  druses 
of  four-sided  prisms  with  straight 
terminal  surfaces  which  remind 
one  of  those  of  the  urate  of  soda. 


Fig.  288.  Crystals  of  uric  acid   from  the 
acid  fermentation  of  the  urine. 


URINARY    ORGANS. 


531 


That  these,  however,  are  not  the  only  crystalline  forms  of 
uric  acid,  that  the  latter  much  more  presents  the  greatest 
changes,  is  well  known. 

If  the  acid  with  which  we  are  occupied  be  precipitated  from 


Fig.  289.  Crystals  of  uric  acid  artificially 
precipitated. 


Fig.  290.  Uric  acid  in  its  various 
crystalline  forms.  At  a  a  a  crystals 
such  as  are  obtained  by  the  decom- 
position of  uric  acid  salts ;  at  ft, 
crystallizations  of  uric  acid  from  the 
human  urine  ;  at  c,  so-called  dumb- 
bells. 


fresh  urine  by  the  addition  of  several  drops  of  muriatic  acid, 
large,  tinged,  often  peculiar  forms  of  crystals  are  produced,  a 
few  of  which  are  represented  by  our  fig.  289.  Other  forms  are 
obtained  by  precipitating  the  pure  uric  acid  (it  is  to  be  dis- 
solved in  a  solution  of  potassa  and  the  potash  salt  reduced  by 
means  of  muriatic  acid).  The  forms  a  of  our  fig.  290  are  then 
produced. 

Abortive  forms  of  the  uric  acid  crystals  constitute  those  pe- 
culiar masses  of  the  figure  c.  They  have  been  called  "  dumb- 
bells." Their  form  is  partly  that  of  a  drum-stick,  partly  that 
of  the  dumb-bells  used  by  gymnasts.  They  occur  at  times  natu- 
rally in  the  urine,  at  times  artificially,  from  the  decomposition 
of  urate  of  potash. 

The  surprising  variety  of  forms  in  which  we  meet  with  the 
uric  acid  crystals  sometimes  make  it  very  desirable  for  the  mi- 
croscopist  to  test  them  chemically  under  his  instrument.  This 


532  SECTION    TWENTIETH. 

may  be  done  with  great  facility.  By  the  addition  of  a  few 
drops  of  a  potash  solution,  the  crystals  in  question  may  be  dis- 
solved, to  be  then  reprecipitated  in  the  ordinary  crystalline 
forms  (fig.  290,  a)  by  the  aid  of  muriatic  acid. 


Fig.  291.  Crys- 
tals of  the  oxalate 
of  lime. 

Fig.  292.  Various  crystalline  forms  of 
chloride  of  sodium,  mostly  from  animal 
fluids. 

The  acid  fermentation  not  unfrequently  leads  to  the  precipi- 
tation of  crystals  of  the  oxalate  of 
lime,  the  familiar  octohedra  which 
are  shown  by  our  fig.  291.  Under 
what  conditions  this  combination 
here  takes  place  has  not  yet  been 
determined.  They  may  also  occur 
rig.  293.  crystals  of  ammonio-phosphate  m  neutral  and  alkaline  urine,  and 

of  magnesia. 

may  likewise  form  constituents  ot 

pathological  sediments.  Chloride  of  sodium  (fig.  292)  also  as- 
sumes the  form  of  octohedra  from  the  presence  of  urea.  In 
consequence  of  its  ready  solubility,  however,  it  never  crystal- 
lizes from  fluid  urine.  To  demonstrate  it,  the  drop  of  fluid 
must  be  allowed  to  evaporate. 

Numerous  small  fermentative  fungi  make  their  appearance 
in  the  urine  as  a  sign  of  the  acid  fermentation.  They  quite 
remind  one  of  the  yeast  fungus  (Cryptococcus  cerevisise),  but 
are  smaller.  Comp.  fig.  295  (to  the  right  and  below. 

If  the  urine  remains  standing  for  a  longer  time  after  its 
evacuation  it  becomes  decomposed,  and  the  fluid  assumes  a  neu- 


UEINAEY    OEGANS. 


533 


tral  and  subsequently  an  alkaline  condition,  produced  by  the 
decomposition  of  the  urea  into  carbonate  of  ammonia.  The 
urine  hereby  grows  somewhat  paler ;  the  former  sediments  dis- 
appear, it  becomes  more  and  more  offensive  to  the  smell,  is 


Fig.  294.  Precipitates  of  the  urate  of  ammo- 
nia from  alkaline  urine,  together  with  crystals 
of  the  oxalate  of  lime  and  ammouio-phosphata 
of  magnesia. 


Fig.  295.    Fermentation — mould  and  vibri- 
onic  formations  in  the  urine. 


cloudy,  a  whitish  pellicle  is  formed  on  its  surface,  and  a  simi- 
larly colored  sediment  is  deposited  at  the  bottom  of  the  vessel. 
This  consists  of  the  familiar  crystals  of  the  ammonio-phosphate 
of  magnesia  (fig.  293).  The  precipitates  of  the  urate  of  ammo- 
nia also  show  themselves.  This  consists  of  strongly  contoured, 
often  quite  dark  globules,  which  are  frequently  covered  -with 
fine  points,  and  thus  remind  one  of  morning  stars,  or  they  may 
also  have  club-like,  corrugated  processes  on  them,  and  thereby 
assume  an  appearance  similar  to  bone-cells.  Fine  needle-shaped 
masses  may  also  be  met  with.  Fig.  294  represents  these  con- 
ditions, together  with  crystals  of  the  oxalate  of  lime  and  the 
arnmonio-phosphate  of  magnesia. 

The  fermentative  fungus  also  disappears  from  the  acid  urine, 
and  in  its  place  appear  the  elements  of  mould  and  numerous 
conf ervoid  growths.  Numerous  fine  granular  masses,  vibrionae, 


534 


SECTION   TWENTIETH. 


likewise  make  their  appearance.  Our  fig.  295  may,  in  its  mid- 
dle portion,  represent  such  mould  formations,  while  to  the  left 
and  below  vibrionse  are  delineated.  The  upper  portion  is  occu- 
pied by  the  fungus  of  the  cryptococcus  cerevisiae  from  yeast, 
the  right  lower  corner  by  the  fermentative  fungus  of  diabetic 
urine. 

Alkaline  fermentation  of  the  urine  may  take  place,  in  an  ab- 
normal manner,  very  soon  after  its  evacuation.  In  consequence 
of  the  fermentative  action  of  the  mucus  and  pus  of  the  bladder, 
urine  which  has  been  retained  there  is  decomposed  into  carbon- 
ate of  ammonia,  and  may  thus  be  evacuated  in  an  alkaline  con- 
dition. The  needle-shaped  groups  of  urate  of  ammonia  repre- 
sented in  the  upper  part  of  fig.  294  came  from  such  urine  in  a 
case  of  paralysis  of  the  bladder. 


Fig.  296.   Crystals  of  cystine. 

Spontaneous  deposits  of  other  matters  are  rare  phenomena. 
In  a  few  cases  only  have  crystals  of  cystine — those  readily 
recognizable,  delicate  six-sided  tables,  such  as  are  represented 
by  fig.  296 — been  found  in  human  urine. 

The  remarkable  and  rapid  destruction  of  the  liver-cells,  which 
has  received  the  name  of  yellow  atrophy  of  the  liver,  has  been 
mentioned  on  earlier  pages  of  this  book  (p.  471),  and  it  was 
remarked  that  this  degeneration  produced  large  quantities  of 


URINARY    ORGANS. 


535 


leucine  and  tyrosine.  These,  excreted  by  the  kidneys,  appear  in 
the  urine  of  such  patients.  Brownish  spherical  druses  of  tyro- 
sine  have  been  noticed  in  the  urinary  sediment  deposited.  A 
drop  evaporated  on  the  microscopic  glass  slide  shows  yellowish 
tyrosine  druses  embedded  between  membraniform  and  globular 
deposits  of  leucine  (Frerichs). 

Among  the  remaining  precipitates  of  urinary  constituents 
which  are  only  to  be  obtained  as  a  result  of  further  chemical 
procedures,  let  us  here  mention  only  the  crystalline  forms  of 
combinations  of  urea  with  nitric  and  oxalic  acids  (fig.  297). 
Their  production,  as  also  the  occurrence  of  other  matters,  such 
as  sarcocine,  xanthine,  etc.,  we  must  leave  to  the  text-books  on 
physiological  chemistry. 


Fig.  297.    Crystals  of  the  combinations  of  urea  with  nitric  and  oxalic  acid,    a  a,  nitrate,  6  &, 
oxalate  of  urea. 

The  anatomical  methods  of  examining  the  various  sediments 
of  the  urine  are  of  a  very  simple  nature.  After  standing  for 
some  time,  the  clear  fluid  is  poured  from  the  vessel  and  the  re- 
mainder is  placed  in  a  watch-glass,  glass  box,  or  glass  beaker, 
from  which  a  drop  is  to  be  removed  by  means  of  a  glass  rod  or 
a  pipette  and  placed  on  the  microscopic  glass  slide.  It  is  con- 
venient to  have  a  small  burette  with  a  caoutchouc  tube  and 
clamp,  after  the  manner  of  the  larger  one  used  fortitrition  (fig. 
74,  1,  p.  145),  with  a  fine  glass  tube  for  the  exit.  The  burette 
is  to  be  filled  with  the  sediment,  or  the  still  clear  urine  which 


536 


SECTION   TWENTIETH. 


is  to  form  a  sediment,  and  the  drops  are  allowed  to  flow  on  to 
the  slide  by  opening  the  clamp. 

With  regard  to  the  preservation  of  urinary  sediments  in  the 
form  of  objects  for  a  collection,  it  may  be  stated  that  those 
which  consist  of  tissue  elements  are  not  capable  of  being  kept 
permanently.  Crystalline  sediments,  on  the  contrary,  are  to  be 
allowed  to  dry  on  a  glass  slide  and  then  mounted  with  Canada 
balsam. 


Fig.  298.  Cortex  of  the  human 
supra-renal  gland  in  vertical  sec- 
tion, a,  smaller,  6,  larger  gland- 
cylindera ;  c,  capsule. 


Fig.  299.  Cortex  of  the  hu- 
man supra-renal  gland  more 
strongly  magnified,  o,  gland- 
cylinder;  6,  interstitial  con- 
nective tissue. 


A  few  words  may  be  devoted,  at  the  close  of  this  section,  to 
the  supra-renal  glands.  These  organs,  which  are  remarkably 
developed  in  the  earlier  foetal  period,  occur  in  a  less  vigorous 
condition  in  the  adult,  and  are  then  frequently  very  fatty, 
almost  fatty  degenerated.  They  show,  as  is  known,  a  firmer, 
reddish-yellow  cortex  (fig.  298)  which,  in  human  beings,  also  per- 
mits of  the  recognition  of  a  narrow,  darker,  and,  after  death, 
not  unfrequently  liquefying  inner  zone,  and  a  softer,  grayish- 
red  medullary  substance.  The  former  (fig.  299)  consists  of  the 


URINARY    OKGANS.  537 

same  connective-tissue  stroma  (b)  which  we  have  already 
described  for  the  hypophysis  cerebri  and  thyroid  gland,  and 
whicli  is  prolonged  inwards  from  the  capsule  in  radiated  la- 
mellae. Numerous  cavities  are  found  in  it ;  they  grow  smaller 
and  smaller  in  an  outward  direction  (fig.  298  a) ;  in  the  middle 
they  are  oblong  and  cylindrical  (V).  Their  contents  are  a  vary- 
ing number  of  granular  cells.  In  the  medullary  substance 
there  is  a  much  finer  connective-tissue  stroma  which  contains 
transversely  oval  cavities  filled  with  variable  cells,  but  which 
contain  but  little  fat.  The  latter,  but  not  the  cellular  elements 
of  the  cortex,  become  brown  in  a  remarkable  manner,  as  Henle 
found,  from  the  action  of  bichromate  of  potash.  In  certain 
mammalial  animals  the  medullary  substance  is  very  rich  in 
nervous  plexuses  containing  ganglion-cells,  and,  indeed,  a  con- 
nection of  our  organ  with  the  embryonic  sympathetic  can 
scarcely  be  denied.  The  number  of  the  blood-vessels  is  also 
quite  considerable.  Delicate  fine  capillaries,  formed  from  the 
numerous  smaller  arterial  branches  from  the  capsule,  encircle 
the  cavities  of  the  cortex  and  pass  over  into  a  highly  developed 
venous  network.  The  vessels  of  this  network  are,  however,  in- 
creased in  diameter ;  they  pass  through  the  connective  tissue  of 
the  medulla  and  lead  into  the  large  single  or  double  veins 
which  lie  in  the  interior  of  the  organ.  The  lymphatics  require 
more  accurate  investigation ;  the  puncturing  method  has  thus 
far  yielded  me  no  results,  while  the  blood-vessels,  for  example, 
those  of  the  calf,  may  be  readily  injected  by  the  artery  as  well 
as  by  the  vein.  Yery  handsome  injections  may  be  obtained 
with  the  Guinea-pig,  as  well  as  the  rat,  from  the  aorta  and 
lower  vena  cava.  _v 

The  supra-renal  bodies  of  the  new-born  and  very  young  ani- 
mals, and  also  those  of  embryos,  from  the  later  periods  of 
embryonic  life,  are  to  be  selected  for  examination. 

Some  things  may  be  recognized,  even  in  sections  from  fresh 
organs,  with  the  aid  of  acids  and  alkalies.  Far  better  views  are 
afforded  by  supra-renal  glands,  which  have  been  hardened  in 
chromic  acid,  Milller's  fluid,  or  absolute  alcohol,  with  the  as- 
sistance of  brushing  and  tingeing.  The  nerves  may  be  studied 
on  the  fresh  organ  with  the  addition  of  alkalies,  or  on  prepara- 


538  SECTION    TWENTIETH. 

tions  which  have  been  immersed  in  dilute  acetic  or  pyroligneous 
acid,  as  well  as  in  weak  chromic  acid.  Sections  deprived  of 
their  water  by  means  of  absolute  alcohol  are  to  be  mounted  in 
Canada  balsam,  or,  when  moist,  in  glycerine. 


Section 


SEXUAL  ORGANS. 

AMONG  the  female  generative  organs  the  uterus  and  the  lac- 
teal glands  are  the  most  important. 

The  ovary  (fig.  300)  shows,  as  is  known,  the  rounded,  closed 
glandular  capsule  (5  c)  which  contains  the  primitive  ovum  em- 
bedded in  a  firm  connective-tissue  framework  or  stroma.  These 


Fig.  300.  The  ovary,  or,  The  stroma ;  &,  smaller 
Graaflan  follicles  ;  c,  a  larger  one  ;  rf,  a  fresh  corpus 
luteum,  with  the  proliferated  cell-layer  of  the  inner 
surface  *  ;  e,  an  old  corpus  luteum  ;  g,  veins  with 
their  ramifications,  /,  in  the  organ. 

Fig.  301.  The  mammalial  ovum.  1.  One  which,  by  a  rapture  of  the  envelope,  «,  of  the  ovum, 
permits  of  the  partial  escape,  6  *,  of  the  yolk,  6 ,-  c,  the  expelled  germinal  vesicle  with  the  ger- 
minal spot,  d.  2.  A  ripe  ovum,  covered  by  epithelial  cells,  c,  arranged  in  a  radiated  manner, 
with  the  chorion,  a,  and  the  yolk,  6. 

ova  are  set  free  by  the  rupture  of  this  capsule,  or  the  Graafian 
follicle ;  this  takes  place  in  the  human  female  at  periods  of 
four  weeks,  corresponding  to  those  of  menstruation ;  in  the 


540  SECTION    TWENTY-FIRST. 

mammalia  it  occurs  at  the  period  of  heat.  The  follicle  itself 
cicatrizes  by  a  connective-tissue  formation,  and  disappears.  By 
this  metamorphosis  it  produces  the  so-called  corpus  luteum  (d  e). 


Fig.  302.  Mature  follicle,  a,  Ovum :  epithelial  stratum  covering  the  same,  &,  and  lining  the  cavi- 
ty, c ;  d,  connective-tissue  wall ;  e,  outer  surface  of  the  follicle. 

If  one  desires  to  obtain  a  primary  view  of  the  ovum  (figs.  301 
and  302  a\  this  most  beautiful  cell-formation  of  the  body,  the  ova- 
rium  of  a  mammalial  animal  just  killed  is  to  be  used.  The  larger 
Graafian  follicles  (fig.  302)  may  be  readily  cut  out  from  the  stroma 
with  a  curved  scissors  and  opened  on  the  microscopic  glass-slide. 
The  ovum  may  be  perceived  as  a  small  white  point  in  the  ex- 
uding, slightly  cloudy  contents,  by  a  sharp  eye,  even  without  any 
further  accessories  ;  while  a  less  perfect  organ  of  vision  requires 
a  loupe,  or  the  very  weak  magnifying  power  of  a  microscope,  for 
its  discovery.  The  adherent,  frequently  thick  covering  of  folli- 
cular  epithelium  (fig.  301,  2  c  /  fig.  302  5)  is  to  be  removed  by 
means  of  a  cataract  needle ;  a  very  thin  and  light  covering 
glass  is  to  be  used,  with  the  interposition  of  a  piece  of  human 
hair.  The  cell  capsule,  zona  pellucida  (fig.  301,  1  #,  2  a\  the 
contents,  the  yolk  (1  £,  2  J)  and  the  nucleolus,  the  so-called 
germinal  spot  (d),  may  be  readily  seen  ;  the  recognition  of  the 


SEXUAL    ORGANS.  541 

fine  contours  of  the  germinal  vesicle  of  the  nucleus  (1  c)  will, 
on  the  contrary,  cause  some  difficulty. 

A  3-400-fold  enlargement  is  to  be  employed  for  this  purpose. 
A  cautious  pressure  made  on  the  covering  glass  with  the  point 
of  a  needle,  while  the  observer  looks  through  the  instrument, 
will  then  cause  the  rupture  of  the  thick  envelope  of  the  ovum 
(1  a)  and  permit  of  the  recognition  of  the  nature  of  the  exu- 
ding yolk  substance  (b  b  *),  as  well  as  the  germinal  vesicle  with 
the  germinal  spot. 

With  human  females,  the  freshest  possible  ovaries  of  youth- 
ful individuals  are  to  be  selected,  preferably  those  who  have 
died  suddenly.  Persons  who  have  been  lying  sick  for  a  long 
time,  and  those  of  a  more  advanced  age,  frequently  cease  to 
show  the  ova  with  any  distinctness. 

If  the  trouble  of  separating  the  Graafian  follicles  from  their 
attachments,  especially  the  very  diminutive  ones  of  our  smaller 
mammalial  animals,  be  feared,  the  ovulum  may  also  be  obtained 
by  scraping  the  cut  surface  of  the  ovary.  An  indifferent  fluid 
medium  will  here  be  necessary. 

Young,  smallest  possible  follicles,  carefully  separated  from 
the  stroma,  may  be  reviewed  in  their  totality  with  low  magni- 
fying powers;  in  this  way  they  will  show  the  ovulum,  the 
epithelium,  and  the  parietes  of  the  glandular  capsule. 

The  examination  of  the  fresh  ovaries  may  also  suffice  to  es- 
tablish the  main  points  concerning  the  nature  of  the  framework 
substance,  as  well  as  the  cell  changes  which  take  place  in  the 
corpus  luteum. 

If,  on  the  contrary,  a  more  accurate  analysis  of  the  ovary  is 
to  be  made,  the  fresh  organ  must  be  hardened.  If  the  freezing 
method  be  omitted,  the  ordinary  fluids  are  to  be  employed, 
among  these  I  would  give  the  first  place  to  absolute  alcohol  and 
chromate  of  potash.  The  blood-vessels  should  also,  when  pos- 
sible, be  previously  injected.  Tingeing  with  carmine,  combined 
generally  with  washing  in  acetic  acid  water,  constitutes  an 
additional  excellent  accessory. 

The  connective-tissue  framework  forms  towards  the  centre  a 
nucleus  of  the  organ,  and  is  extremely  rich  in  blood  and  lymph 
vessels ;  externally  it  is  a  non-vascular  framework,  in  the  smaller 


542 


SECTION    TWENTY-FIRST. 


and  larger  spaces  of  which  are  contained  the  ova.     The  young- 
est of  the  latter  appear  in  extraordinary  numbers  in  its  periph- 


Fig.  SOS.  Ovary  of  the  rabbit,     a,  epithelium  (serosa) ;  &,  cortical  or  external  fibrous  layer ;  c, 
youngest  follicles ;  d,  a  somewhat  more  developed  older  one. 

eral  portion  (fig.  303  c  d),  the  "  zone  of  the  primordial  folli- 
cles." Here  lie  the  most  unripe  ova,  beautiful  cells  without  en- 
velopes, surrounded  by  a  mantle  of  small, 
epithelium-like  elements  (fig.  304, 1).  The 
developing  ovulum  (2)  soon  shows  the  latter 
cells  as  a  double  layer,  and  on  it  itself  a 
capsule,  the  zona  pellucida  (2  a)  is  perceiv- 
ed. A  cavity  (fig.  303  d)  is  afterwards  form- 
ed by  the  separation  of  the  follicular  epithe- 
lium, and  finally  we  receive  the  appearance 
of  the  ripe  follicle,  represented  in  fig.  302. 
The  latter  occur  only  in  limited  numbers  in 
the  ovarium.  They  have  a  connective-tis- 
sue wall.  An  inner  stratum  (d)  shows  an 
extraordinarily  rich  network  of  capillaries, 
while  larger  vessels  are  contained  in  a  more 
peripheral  layer.  If  we  add  the  layer  d 
of  our  fig.  303  as  a  connective-tissue  bound- 
ary layer  to  the  organ,  and  remark,  finally,  that  a  stratum  of 


Fig.  304.  Youngest  folli- 
cles from  the  ovary  of  the 
rabbit.  At  1  the  ovulum  a 
is  still  withbut  a  zona  pellu- 
cida ;  at  2  this  commences 
to  surround  the  ovum  a. 


SEXUAL    ORGANS. 


543 


cylindrical  cells,  the  ovarian  or  germinal  epithelium  (<?/),  covers 
the  surface,  then  we  have  presented  in  a  few  sentences  an  out- 
line of  the  structure  of  the  ovary. 

Fine  transverse  sections  of  the  hardened  ovary  show  these 
relations  without  difficulty.  If  the  plane  of  the  section  be 
favorable,  the  ovulum  may  also  be  perceived  in  large  folli- 
cles, embedded  in  the  epithelial  layers  of  the  latter  (very  fre- 
quently lying  to  the  inner  side).  Occasionally,  with  strongly 
hardened  ovaries,  such  fine  sections  of  the  smaller  follicles  may 
be  obtained  with  a  sharp  knife,  that  the  ovulum  may  likewise 
be  seen  in  the  section ;  sometimes  only  the  zona,  after  the  loss 
of  the  yolk  and  nucleus. 

We  have  more  recently  received  very  important  information, 
through  Pfliiger,  concerning  the  formation  of  the  Graafian  fol- 
licles, which  established  the  truth 
of  the  older  but  no  longer  re- 
garded observations  of  Valentine 
and  Billroth,  and  afforded  an  in- 
teresting parallel  between  the 
testicle  and  the  ovary.  Other 
observers  afterwards  coincided, 
and  Waldeyer  has  produced  a 
beautiful  monograph.  Accord- 
ing to  this,  the  ovary  consists 
originally  of  ordinary  oblong, 
occasionally,  however,  also  of 
quite  irregularly  formed  cell-ag- 
gregations, the  f oflicular  chains  or 
ovular  strands  (fig.  305).  In  these 
primordial  follicular  rudiments 
are  formed  the  ova ;  the  follicles 
become  separated  from  them 
by  constriction,  but  may  still  re- 
main connected  with  each  other 
in  rows,  and  may  continue  to  in- 
crease in  size  (Pniiger's  "  follicu- 
lar chains  ").  The  whole  formation,  although  possibly  it  may 
also  repeat  itself  in  after-life,  is,  however,  very  transitory,  and  was 


Fig.  305.  Follicular  chains  from  the  ovary 
of  tbe  calf.  1.  With  ova  forming.  2.  At 
a,  showing  the  constriction  into  a  Graaflan 
vesicle. 


544  SECTION"   TWENTY-FIKST. 

consequently  overlooked  for  so  long  a  time.  Young  kittens  in 
tlie  first  weeks  of  their  life  are  to  be  recommended  here ;  as 
fluids,  weaker  solutions  of  chromate  of  potash,  or  the  Muller's 
eye-fluid.  A  stratum  of  free  ovum  cells,  which  is  said  to  have 
been  observed  close  under  the  surface  of  the  ovary  (Sehron, 
Grohe),  does  not  exist,  as  the  small  cells  of  the  so-called  forma- 
tio  granulosa  surrounding  these  ovula  were  destroyed  by  the 
action  of  the  reagents  (alcohol  and  strong  chromic  acid). 

ISTow  whence  came  the  ovular  strands  and  the  ovules  which 
they  contain  ? 

The  peculiar  ovarian  epithelium,  which  we  have  previously 
mentioned,  sends  conical  proliferations  into  the  peripheral  stra- 
tum of  the  organ.  Some  of  the  cells  of  the  cone  become  ova, 
and  by  separation  from  the  epithelial  matrix  the  ovular  strand 
is  formed. 

The  Graafian  follicle  constantly  approaches  the  surface  of 
the  organ  in  proportion  as  it  approaches  its  maturity,  so  that, 
finally,  entirely  matured,  it  is  only  covered  by  a  thin  fibrous 
layer  of  the  albuginea. 

It  is  well  known  that  as  a  result  of  increased  congestion  of 
the  walls  of  the  follicle,  the  collection  of  fluid  in  a  Graafian 
vesicle  becomes  greater  and  greater,  and  that  thus  a  rupture  of 
the  latter  may  take  place,  naturally  at  the  point  of  the  slightest 
resistance,  that  is,  at  the  surface  of  the  ovary. 

This  bursting  of  the  follicular  walls,  which  frees  the  ovulum 
and  renders  its  further  development  possible,  is  also  promoted 
by  still  another  phenomenon,  a  cell-proliferation  at  the  base 
and  on  the  lateral  walls  of  the  follicle. 

A  recently  ruptured  follicle  of  the  human  female  occasion- 
ally presents  us  a  lump  of  coagulated  blood  (coming  from  the 
lacerated  parietal  vessels),  but  always,  however,  the  layer  of 
plicated  substance  which  has  a  yellowish  appearance  from  the 
fat  it  contains.  Our  fig.  300  at  d*  shows  this  proliferating 
stratum,  which  probably  consists  of  derivatives  from  the  cap- 
sular  epithelium,  but  principally,  however,  of  the  cells  of  the 
inner  parietal  layer,  and  which  also,  at  this  time,  contains  nu- 
merous emigrated  lymphoid  cells  (Waldeyer).  "While  a  portion 
of  these  cells  are  destroyed  by  fatty  degeneration,  an  active 


SEXUAL     ORGANS.  545 

formative  process  is  maintained  in  others,  in  consequence  of 
which  a  vascular  young  connective  tissue  is  formed,  which 
diminishes  the  interior  space  more  and  more,  and  not  only 
completely  fills  the  cavity  of  the  follicle,  but  also  causes  a  con- 
siderable hypertrophy.  The  presence,  at  this  time,  of  a  rich 
delicate  vascular  network  in  the  corpus  luteum  is  proved  by  in- 
jection. We  recommend  for  this  readily  practicable  experi- 
ment the  ovarium  of  the  sow,  in  which  the  oviducts  and  uterus 
also  afford  very  handsome  objects. 

The  progressive  metamorphosis  has  herewith  reached  its 
height.  The  young  connective-tissue  contained  substance  shriv- 
els more  and  more  (probably  with  a  simultaneous  atrophy  of  the 
vessels),  the  tissue  becomes  firmer,  more  like  a  cicatrix.  Such 
remains  of  the  corpus  luteum  may  still  be  seen  for  a  longer 
period.  The  whole  process,  however,  proceeds  much  more 
rapidly  in  a  corpus  luteum  caused  by  an  ordinary  menstruation 
than  in  one  where  the  escaped  ovum  has  been  impregnated.  It 
has  been  asserted,  in  accordance  herewith,  that  there  are  two 
forms  of  the  corpora  lutea. 

In   the   portion  of    the  blood -clot  ^. 

which  remains  behind,  the  crystalliza-  B    ~\ 

tion  of  the  kaematoidine  (fig.  306), 
which  we  have  already  mentioned, 
takes  place. 

Among  the  pathological  occur- 
rences, the  formations  of  cysts  are, 
as  the  practical  physician  knows,  of 
extraordinary  frequency  in  the  human 
ovaries.  A  portion  of  these — and,  }/ 

indeed,  the  greater— certainly  cor-  PI&m  Grystals  of  ha3matoidine. 
respond  to  hydropically  distended 

Graafian  vesicles.  Others  of  these  formations  originate,  on  the 
contrary,  from  a  proliferation  of  the  stroma  of  the  ovarium. 
The  walls  are  formed  of  connective-tissue  substance,  and  the 
mucilaginous  contents  of  colloid  degenerated  confluent  cells. 
Innumerable  quantities  of  such  structures,  with  very  slight 
dimensions,  may  be  found  in  an  ovary.  A  number  of  larger 
ones  mav  be  met  with,  or  one  grown  to  a  gigantic  size  may  be 
35 


546  SECTION   TWENTY-FIEST. 

found.  The  most  remarkable  form  of  ovarian  cyst  is  that, 
however,  where  a  part  of  the  parietes  has  assumed  the  structure 
of  the  corium,  with  papillae,  hair-follicles,  sebaceous  and  sudori- 
parous glands,  and  where  hairs,  occasionally  united  into  long 
bundles,  are  met  with  (dermoid  cysts).  Even  teeth,  pieces  of 
bone,  and  hyaline  cartilage  may  be  found  in  such  cysts.  The 
remaining  contents  are  formed  by  a  pap-like  mass,  consisting 
of  desquamated  epithelium,  fat  molecules,  and  crystals  of 
cholesterine.  (Similar  capsules,  with  such  strange  contents,  have 
also  been  found  in  other  organs ;  for  instance,  in  the  lungs.)  An 
explanation  of  the  remarkable  production  is,  at  the  present 
time,  impossible. 

The  contents  are  to  be  examined  in  the  fresh  condition, 
bones  and  teeth  after  the  manner  of  the  normal  structures,  and 
the  walls  on  objects  hardened  by  means  of  alcohol. 

Preparations  of  the  ovaries,  tinged  and  deprived  of  their 
water  by  means  of  alcohol,  may  be  very  suitably  mounted  in 
Canada  balsam ;  otherwise,  dilute  glycerine  is  to  be  selected. 

Concerning  the  efferent  passages,  the  oviducts,  it  may  be 
said  that  their  mucous  membranes,  muscular  and  serous  layers, 
are  to  be  examined  in  the  same  manner  as  those  of  other  large 
glandular  canals.  The  ciliated  epithelium  requires  quite  fresh 
objects;  a  previous  hardening  is  most  suitable  for  the  re- 
mainder. 

The  womb  or  uterus  also  possesses  an  epithelial  layer  formed 
of  ciliated  cells,  and  a  tubular-shaped  mucous  membrane  con- 
taining glands.  These  tubular  follicles,  lined  with  cylindrical 
cells,  are  to  be  observed  in  fresh  female  mammalial  animals, 
partly  immediately,  partly  after  hardening,  by  means  of  vertical 
and  horizontal  sections.  In  the  human  female  the  uterine 
follicles  appear  particularly  fine  during  menstruation  or  in  the 
first  months  of  pregnancy. 

The  increase  in  volume  of  the  womb  during  pregnancy  is 
exhibited  principally  by  its  muscular  portion,  which  consists  of 
contractile  fibre-cells.  We  first  see  an  increased  growth  of 
these  elements,  in  part  into  structures  of  gigantic  length.  Even 
on  this  account  the  massiveness  of  the  muscular  portion  must 
be  considerably  increased.  Besides  this,  a  new  formation  of 


SEXUAL    OBGANS.  547 

such  muscular  cells  also  takes  place  (although  in  its  details  not 
yet  explained),  especially  in  the  iirst  half  of  pregnancy.  The 
mucous  membrane  also  increases  considerably,  becomes  loosened 
in  its  connection  with  the  muscular  layer,  and  forms  the  decidua 
of  the  ovum. 

After  the  birth  the  contractile  fibre-cells  return  to  a  shorter 
length;  a  part  of  them 'are,  however,  without  doubt,  destroyed 
by  fatty  degeneration.  Numerous  depositions  of  small  fat 
molecules  in  the  fibre-cells  are,  besides,  a  quite  extended  phe- 
nomenon. 

The  remains  of  the  mucous  membrane  are  then  removed  in 
child-bed  by  the  lochial  secretion.  The  manner  in  which  the 
new  mucous  membrane  of  the  uterus  is  formed  requires  more 
accurate  investigation. 

The  energetic  proliferating  vegetation,  the  active  change  of  its 
elements  which  the  uterus  presents  under  abnormal  conditions, 
asserts  itself  in  the  sphere  of  pathology,  and  thus  produces  the 
so  frequent  new  formations,  among  which  the  so-called  fibroid, 
hard  fibrous  tumors,  are  the  most  widely  diffused.  These  con- 
sist sometimes  exclusively  of  fibrillated  connective  tissue  perme- 
ated by  blood-vessels,  sometimes  of  the  above,  mingled  with 
contractile  fibre-cells,  occasionally,  however,  also,  almost  en- 
tirely of  smooth  muscular  tissue.  They  supplant  the  normal 
tissue  in  proportion  to  their  growth.  If  connected  with  the 
wall  of  the  organ  by  means  of  a  pedicle,  they  are  called  uterine 
polypi.  Their  examination  is  to  be  made  in  accordance  with 
the  directions  which  have  been  given  for  the  developed  connec- 
tive tissue. 

Cancerous  tumors  of  the  womb  are  also  of  frequent  occur- 
rence. They  frequently  appear  in  the  form  of  epithelial  can- 
cer. 

We  may  pass  over  the  methods  of  investigating  the  uterus, 
the  vagina,  and  the  external  genitals.  The  accessories  are  in 
part  the  same  as  those  which  we  have  already  mentioned  above 
for  mucous  membranes  and  smooth  muscles,  in  part  those  of  the 
skin,  which  are  to  be  discussed  in  the  following  section.  Let 
it  here  be  mentioned,  however,  that  it  has  been  recommended 
for  the  uterine  muscular  tissue  to  boil  the  uterus  for  a  few 


548  SECTION   TWENTY-FIKST. 

minutes,  and  to  join  with  this  an  immersion  in  carbonate  of  pot- 
ash. Furthermore,  the  maceration  in  pyroligneous  acid,  and 
the  employment  of  alcohol,  with  subsequent  drying,  after  which 
thin  sections  are  to  be  exposed  to  the  action  of  the  20  per  cent, 
nitric  acid. 

Cabinet  preparations  of  the  tissue  of  the  womb  and  of  the  tex- 
tures of  the  external  genitals  are  to  be  prepared  by  the  methods 
now  employed  for  the  mucous  membrane,  the  skin,  and  the  mus- 
cular tissue. 

The  mucous  secretion  of  the  female  genitals  originates  first 
and  principally  from  the  cervix  uteri,  the  mucous  membrane 
of  which  contains  numerous  fossae  or  mucous  follicles ;  and  then 
from  the  glandless  vaginal  mucous  membrane.  The  former 
has  an  alkaline  reaction,  appears  hyaline,  tough,  arid  tenacious, 
and  contains  numerous  mucous  corpuscles  together  with  scanty 
pavement  epithelial  cells.  In  contact  with  the  acid  vaginal 
mucus  it  becomes  cloudy.  The  latter,  an  almost  limpid  fluid 
substance,  is  very  scanty  in  young  maiden  bodies,  except  dur- 
ing the  menstrual  periods ;  in  blennorrhoeas  of  the  genital  mu- 
cous membrane,  as  well  as  with  women  far  advanced  in  preg- 
nancy, it  increases  in  quantity,  and  the  vaginal  mucus  becomes 
cloudy,  milk-  or  pus-like.  The  elements  of  the  vaginal  secre- 
tion, which  are  shown  by  the  microscope  to  increase  in  quantity 
in  proportion  to  the  increase  of  consistence  and  opacity,  are 
again  mucous  corpuscles  and  pavement  epithelium. 

In  the  vaginal  mucus  of  non-pregnant  persons,  but  especially, 
however,  in  the  pregnant,  there  occurs,  together  with  several 
vegetable  parasites,  an  interesting  animal  parasite,  the  Triclio- 
monas  vaginalis,  discovered  by  Donne.  This  is  an  infusorium 
which  is  provided  with  a  flagellum  and  vibratile  cilise ;  it 
moves  actively  in  pure  mucus,  but  very  sluggishly,  on  the  con- 
trary, in  that  diluted  with  water.  This  infusorium  appears  to 
be  entirely  absent  from  the  normal  secretion  of  the  vagina  of 
unimpregnated  females  (Kolliker  and  Scanzoui). 

A  speculum  is  to  be  employed  in  order  to  obtain  the  secretion 
in  question.  The  vaginal  mucus  may  be  obtained  by  scraping 
with  a  spatula.  It  is  difficult  to  obtain  the  mucus  from  the 
cervix  unmixed  with  vaginal  secretion.  The  addition  of  water 


SEXUAL    OEGANS. 


549 


is  naturally  to  be  avoided  in  the  microscopical  examination  of 
the  Trichomonas. 

The  menstrual  blood  from  the  ruptured  capillaries  of  the 
uterine  mucous  membrane  has  usually  (perhaps  from  the 
admixture  of  secretions  from  the  mucous  membrane)  lost  its 
coagulability.  It  shows,  together  with  the  blood-cells,  numer- 
ous granulated  structures,  mucous  corpuscles,  also  separated 
ciliated  cells  which  have  lost  their  vibratory  cilise.  Shreds  or 
connected  masses  of  the  uterine  mucous  membrane  may  be 
caused  by  more  considerable  separations,  so  that  a  formal 
decidua  spuria  has  been  spoken  of. 


f  Fig.  307.  1.  Rudiment  of  the 
lacteal  gland  in  the  foetus,  a  6, 
Epidermis;  c,  cell  aggregation; 
d,  fibrous  layer.  2.  From  a 
seven-months'  foetus,  a,  central 
substance  ;  6,  larger,  <v  smaller 
outgrowths. 


Fig.  308.  The  milk-gland  of  another  em- 
bryo, a,  The  central  club-like  mass,  with 
smaller  internal,  &,  and  larger  external,  c,  out- 
growths. 


The  lochial  secretion  consists  at  first  almost  entirely  of  blood 
which  comes  from  the  torn  vessels  of  the  contracting  uterus. 
In  the  first  days  after  the  birth,  when  a  brown-red  mucous  fluid, 
with  a  few  flakes  and  shreds,  usually  corne  away,  the  micro- 
scope shows  as  elements,  together  with  sometimes  unaltered, 
sometimes  swollen  or  indented  blood-corpuscles,  pavement- 
shaped  cells,  granulated  structures  (mucous  and  pus  cor- 
puscles), effete  cells  as  well  as  their  ruins,  fat-molecules,  and 
likewise,  here  and  there,  cholesterine  tables.  In  the  latter 
periods,  where  the  blood-corpuscles  decrease  more  and  more 


550  SECTION    TWENTY-FIRST. 

in  numbers,  and  finally  disappear  altogether,  the  number  of 
the  granulated  cells  usually  increases  in  an  inverse  ratio. 
Towards  the  end  the  lochial  secretion  gradually  assumes  the 
character  of  a  mucus  rich  in  cells.  The  examination  presents 
no  kind  of  difficulty.  For  its  reception,  flat  oval  plates  may 
be  used  (Werthheimer). 

The  lacteal  glands  are  formed  in  the  fourth  and  fifth  month 
of  human  embryonic  life,  after  the  manner  of  other  cutaneous 
glands,  by  solid  papillary  projections  of  the  foetal  epider- 
moidal  cells,  covered  by  a  fibrous  layer  of  the  corium  (fig.  307, 
1,  d).  Several  weeks  later  (fig.  307,  2,  and  308)  such  a  club- 
like  papilla  (a)  has,  by  division  of  its  cells,  sent  down  new 
papillae,  from  which  the  chief  excretory  passages  are  after- 
wards formed,  which,  by  further  proliferations  of  this  kind, 
produce  the  first  rudiments  of  the  gland-body.  Even  at  the 
hour  of  birth,  however,  a  rudimentary  formation  of  gland 
vesicles  has  not  taken  place,  and,  while  the  ducts  become 
hollow,  their  outgrowths  remain  at  the  stage  of  solid  cell- 
aggregations.  The  larger  gland  divisions  keep  to  the  periph- 
ery, the  smaller  ones  to  the  inner  portions  of  the  whole 
organ. 

The  lacteal  glands  preserve  this  undeveloped,  more  foetal 
character,  even  during  the  period  of  childhood,  in  the  male  as 
well  as  in  the  female  sex. 

While  it  is  true  that  even  here  the  lac-teal  gland  of  the  female 
has  advanced  more  rapidly  than  that  of  the  male,  it  is  only  at 
the  entrance  of  puberty  that  a  further  development  of  the 
former  becomes  energetic.  Numerous  gland-vesicles  are  the 
result.  Nevertheless,  the  organ  still  remains  far  behind  its 
complete  development,  for  which  the  first  pregnancy  is  neces- 
sary. After  the  delivery  it  generally  receives  that  organization. 
Atrophy  is  first  introduced  by  the  period  of  involution ;  fat- 
tissue  takes  the  place  of  the  gland-body. 

The  lacteal  gland  of  the  male,  on  the  contrary,  remains  at 
the  lower  stage  throughout  the  whole  life. 

The  developed  gland  of  the  sexually  mature  female  contains, 
in  a  condition  of  rest,  an  epithelial  lining  of  ordinary  rounded, 
polygonal  gland-cells. 


SEXUAL    OKGANS.  551 

In  the  gland-vesicles  of  the  cow,  the  same  finest  reticnlar 
canal-work  which  we  mentioned  formerly  (p.  459)  at  the  pan- 
creas has  been  injected  (Giannzzi  and  Falaschi). 

The  mammary  gland,  as  is  known,  presents  manifold  patho- 
logical new  formations.  In  many  of  them  the  development 
takes  place  from  the  proper  gland-bodies.  Thus,  for  example, 
at  the  period  of  involution  small  cysts,  filled  with  a  mucila- 
ginous fluid,  are  of  frequent  occurrence.  They  arise  from  a 
metamorphosis  of  the  gland-lobules,  the  distended  vesicles  of 
which  become  united  with  each  other.  New  formations  of 
gland-substance,  under  pathological  conditions,  have  also  been 
ascribed  to  the  organs  under  consideration,  and  have  been 
described  as  "  adenoid "  tumors.  Soft,  but  especially  hard 
cancers,  cysto-sarcoma  and  simple  sarcomatous  tumors  also 
occur.  Concerning  the  point  of  origin,  the  same  uncertainty 
prevails  here  as  elsewhere. 

The  examination  of  the  lacteal  glands  (normal  as  well  as 
diseased)  is,  for  the  most  part,  to  be  made  (in  the  usual  manner) 
on  hardened  organs,  by  means  of  fine  sections.  A  preparatory 
immersion  in  very  dilute  acetic  acid,  in  diluted  pyroligneous 
acid,  or  a  brief  boiling,  is  useful.  For  the  first  rudimentary 
appearances,  human  embryos  at  about  the  fifth  month  are  to  be 
selected ;  for  the  later  appearances,  the  bodies  of  children. 
The  material  necessary  for  the  recognition  of  the  completely 
developed  gland  can  only  be  obtained  from  a  female  who  has 
borne  children.  The  active  organ  may  be  obtained  from  the 
bodies  of  the  lying-in.  Injections  of  the  larger  glandular 
passages  from  the  lacteal  sinuses  succeed  with  tolerable  fa- 
cility ;  the  constant  pressure  is  to  be  employed  for  the  injection 
of  the  finest  passages. 

The  milk  of  the  human  female  and  of  the  mammalia  is 
formed  by  the  liberation  of  the  fat  produced  in  the  cells  of  the 
lacteal  glands,  which  thus  becomes  suspended  in  the  glandular 
fluid,  rich  in  albumen  and  sugar. 

The  secretion  under  consideration  presents  a  near  relation- 
ship, in  this  regard,  with  the  less  fluid  substance  secreted  by 
the  sebaceous  follicles  of  the  external  integument,  and,  in  fact, 
we  are  in  a  position  to  vindicate,  by  the  aid  of  facts  in  em- 


552  SECTION   TWENTY-FIKST. 

bryology,   the   same   manner  of  origin    of   both  varieties   of 
glands. 

Ordinary  milk   shows,  in  a  clear  fluid,   an 
°  o  innumerable  quantity  of  globular  fat-drops,  the 


° 


°na0          so-called  milk  globules  (309  a). 
Q  o®  These,  which  may  be  examined  even  with 

tfj\     medium  powers,  never  flow  together  after  the 
d&\     W     manner  of  free  fat,  but  rather  possess  a  delicate 
^     t>         investment  of   coagulated   casein.     It  is   only 
rig.  309    Eiemen-     when  this  is  dissolved  by  means  of  acetic  acid 
or  alkalies,  that  the  union  of  the  free  drops  of 
fat  is  noticed  under  the  microscope. 

If  the  secretion  of  the  milk  takes  place  less 
energetically,  as  is  the  case  with  the  so-called  colostrum,  and 
the  secretion  which  occurs  during  the  latter  period  of  preg- 
nancy, as  well  as  in  the  first  days  after  the  delivery,  this  rapid 
destruction  of  the  gland-cells  is  absent,  and  we  still  meet  with 
them  in  part  (overloaded  with  fat  to  a  high  degree,  it  is  true) 
as  constituents  of  the  evacuated  fluid.  We  also  meet  with  frag- 
ments of  these  cells  and  membraneless  conglomerations  of  fat. 
These  are  the  so-called  colostrum  corpuscles  of  the  authors 
(fig.  309,  5)  ;  they  do  not  appear  to  be  wholly  without  vital  con- 
tractility (Strieker,  Schwarz).  A  few  remain  for  a  long  time 
in  the  milk  of  women.  A  larger  number  of  such  structures  in 
the  milk,  months  after  the  delivery,  must,  on  the  contrary,  be 
denoted  as  abnormal. 

Abnormal  constituents  of  the  milk  are  of  secondary  import- 
ance. Blood-cells,  and  also  lymphoid  corpuscles,  may  be  met 
with  in  it  ;  their  recognition  is  not  difficult. 

Remarkable  colorations  may  occur  in  milk  which  has  stood 
for  some  time  ;  thus  blue  and  yellow  colors  have  been  observed. 
In  such  cases  the  microscope  has  shown  vibrionic,  and  also 
protococcus  formations. 

A  drop  of  milk  spread  out  in  a  thin  layer  will,  without  any 
further  manipulation,  present  its  elements  to  view  in  the  same 
manner  as  other  cell-containing  fluids,  as,  for  instance,  the  blood. 
Strong  magnifying  powers  are  unnecessary  ;  permanent  preser- 
vation will  hardly  be  undertaken. 


SEXUAL    ORGANS. 


553 


Among  the  parts  of  the  male  generative  organs  we  will  first 
speak  of  the  testicles,  taking  it  for  granted  that  the  coarser 
structural  conditions  are  already  known. 

Numerous,  but  not  complete  connective-tissue  septa,  arising 
from  the  fibrous  tunic  (the  tunica  albuginea)  converge  to  unite, 
in  the  upper  part  of  the  testicle,  in  a  firmly  woven,  connective- 
tissue,  wedge-shaped  mass,  the  so-called  corpus  Highmori.  The 
gland  substance,  consisting  of  reticularly  united  and  convoluted 
canals,  the  so-called  seminal  canaliculi,  is  thereby  divided  into 
conical,  lobular  convolutions. 

The  appearance  of  such  a  seminal  cana- 
licule  may  be  represented  by  the  adjoining 
fig.  310.  The  inner  surface  of  the  mem- 
brana  propria  is  lined  by  a  simple  layer  of 
rounded  polygonal  cells  (£).  A  fibrous  con- 
nective-tissue tunic,  with  longitudinally  ar- 
ranged connective-tissue  corpuscles  (#),  is 
spread  out  externally  around  the  structure- 
less gland-membrane. 

The  cell-body  of  the  glandular  epithelium 
consists,  in  youthful  individuals,  of  a  finely 
granular  substance,  which,  in  later  years, 
becomes  richer  in  fat. 

A  soft,  loose  connective  tissue  is  met 
with  between  the  seminal  canaliculi.  In 
smaller  mammalial  animals  this  is  very 
scanty  and  soft.  * 

The   seminal   canals  then   coalesce   and 
finally  form   a  single  vessel,   a    tolerably 
large  canal,  which,  with  innumerable  convo- 
lutions, forms  the  so-called  body  and  tail  of 
the  epididymis;    it  afterwards   straightens 
and  becomes  the  vas  deferens.     The  epididymis  shows,  in  addi- 
tion, a  ciliated  lining  of  its  convoluted  seminiferous  canals 
(Becker),  in  places  with  gigantic  cells  and  vibratile  cilise. 

The  blood-vessels,  which  are  very  easy  to  inject,  pass  from 
without  and  from  the  corpus  Highmori  into  the  organ,  permeate 
the  septula,  and  finally  encircle  the  seminiferous  canals  with  a 


Fig.  310.  Human  semi- 
nal canaliculi,  with  the 
gland-cells  6  and  the  con- 
nective-tissue tunic  a. 


554  SECTION    TWENTY-FIRST. 

wide-meshed  (but  not  particularly  abundant)  network  of  capil- 
laries. 

The  first  accurate  information  concerning  the  lymphatics 
was  furnished  by  Ludwig  and  Tomsa.  In  fact,  nothing  is 
easier  than  the  injection  of  the  organ  by  means  of  a  puncture. 
A  surprising  picture  of  numerous  vessels  (Ludwig  and  Tomsa) 


Fig.  311.    From  the  testicle  of  the  calf,    a,  seminiferous  canals  seen  in  more  oblique,  6,  in 
more  transverse  sections ;  c,  blood-vessels ;  d,  lymphatics. 

unfolds  itself  here,  and,  as  it  appears,  in  exactly  the  same 
manner  in  all  mammalial  animals.  A  very  extensive  net- 
work of  lymphatics,  with  valves,  lies  under  the  serous  covering, 
permeates  with  its  branches  the  albuginea,  and  spreads  itself 
out  beneath  the  same  to  a  likewise  very  compact  network  of 
passages  enclosed  by  connective  tissue.  Some  of  these  passages 
pass  at  once  between  the  seminal  canals ;  the  greater  portion, 
however,  first  pass  through  the  familiar  septula,  and  finally 
likewise  enter  the  loose  connective  tissue  lying  between  the 
glandular  passages  (fig.  311,  a  5).  The  spaces  of  this  connec- 
tive tissue,  in  so  far  as  they  are  not  occupied  by  seminiferous 
canals  and  blood-vessels  (<?),  are  filled  with  lymphatic  fluid  (d). 
We  meet  with  this  in  a  remarkable  manner,  in  small  mam- 
malial animals  especially,  the  seminal  canals  of  which,  having 
but  very  little  interstitial  connective  tissue,  are  regularly  bathed 
in  lymph.  For  the  recognition  of  the  vascular  cells  of  our 
lymphatics,  either  the  injection  of  a  solution  of  nitrate  of 
silver  or  the  immersion  of  the  sections  in  such  a  solution  of 
4  per  cent,  may  be  employed  (Tommasi). 


SEXUAL    OEGANS.  555 

The  most  frequent  pathological  new  formations  of  the  testicle 
are  soft  tumors,  appearing  in  the  form  of  medullary  carcinoma 
and  sarcoma.  In  the  so-called  c-ysto-sarcoma  we  meet  with 
larger  or  smaller  vesicles  partly  filled  with  water,  partly  with 
colloid  substance,  which  proceed  from  transformations  of  the 
seminal  canals. 

For  the  examination  of  the  testicles,  human  bodies  or  those 
of  larger  mammalial  animals  may  be  selected.  The  canals  of 
the  fresh  organ  may  be  readily  isolated  with  the  preparing- 
needles  and  their  cell-contents  recognized.  Acetic  acid  and 
alkalies  may  thereby  be  suitably  employed.  To  obtain  the 
entire  arrangement  of  the  seminal  canals,  they  are  to  be  in- 
jected with  transparent  cold-flowing  masses  or  with  gelatine. 

Gerlach  gives  us  the  following  directions  for  tho  injection 
of  these  passages  with  gelatine :  The  testicle  is  to  be  placed 
in  a  weak  solution  of  potash  for  4-6  hours,  to  dissolve  out  the 
cells  and  the  entire  contents  as  much  as  possible.  An  attempt 
is  then  to  be  made  to  remove  the  mass  by  cautious  pressure, 
after  which  the  organ  is  to  be  washed  off  in  water.  The  air 
contained  in  the  glandular  canals  is  to  be  drawn  out  as 
thoroughly  as  possible,  and  the  injection  fluid  (colored  with 
carmine  or  chromate  of  lead)  is  to  be  forced  in  very  slowly. 
During  this  procedure  the  organ  should  be  kept  in  warm 
water. 

I  would  here  also  recommend  the  organ  hardened  in  pieces 
in  absolute  alcohol,  that  for  instance  of  the  calf,  in  which 
the  blood  and  lymphatic  vessels  have  been  previously  in- 
jected with  blue  and  red  transparent  substances.  The  vas 
deferens  must  be  studied  hardened  in  fluids.  A  mammalial 
animal  just  killed  is  to  be  used  for  the  ciliated  epithelium  of 
the  epididymis. 

Concerning  the  deeper,  efferent,  and  copulating  organs  of 
the  male  generative  apparatus,  it  may  be  remarked  that  the 
ductus  ejaculatorii  and  seminal  vesicles  have  the  same  structure 
as  the  vas  deferens,  and  are  to  be  examined  in  a  similar 
manner.  In  the  latter  is  found,  together  with  spermatic  fila- 
ments, a  transparent  albuminous  substance,  which  undergoes 
a  gelatinous  coagulation,  to  afterwards  resume  a  fluid  condi- 


556 


SECTION   TWENTY-FIRST. 


tion.  It  is  the  same  substance  which  the  evacuated  sperm  con- 
tains. 

The  prostate,  a  racemose  glandular  aggregation,  is  very  rich 
in  smooth  muscular  tissue.  The  latter  elements  may  be  exam- 
ined in  the  fresh  organ  with  the  reagents  usually  employed 
for  this  tissue,  such  as  the  potash  solution  or  a  20  per  cent, 
nitric  acid.  For  the  investigation  of  its  further  structure,  the 
organ  is  to  be  immersed  in  pyroligneous  acid  or  hardened  in 
alcohol. 

The  prostatic  secretion  appears  to  contain  the  same  albu- 
minous body  which  we  have  just  mentioned  at  the  vesiculse 
seminales.  The  prostatic  stones,  as  they  are  termed,  concen- 


Fig.  312.  From  the  peripheral  portion  of  the  corpus  cavernosum  penis,  by  a  low  magnif yins 
power.  1.  o,  so-called  superficial,  and  &,  deeper  cortical  network.  2.  Insertion  of  arterial 
branches  (a)  in  the  passages  of  the  deeper  cortical  network  (copied  after  Langer.), 

trie  structures,  occasionally  of  considerable  size,  consist  of  this 
substance  (Virchow). 


SEXUAL    OEGANS.  557 

The  glands  of  Cowper  are  to  be  examined  in  the  same  way 
as  other  racemose  glands. 

The  tissue  of  the  cavernous  organs  consists  of  elastic  and 
connective- tissue  fibres,  intermixed  with  smooth  muscles.  The 
latter  are  to  be  studied  in  a  fresh  condition,  the  remainder  on 
alcoholic  preparations,  where  we  would  recommend  the  previous 
injection  with  uncolored  gelatine.  These  also  afford  oppor- 
tunity, especially  in  transverse  sections,  for  studying  the  male 
urethra.  To  follow  the  vascular  arrangement  of  the  corpora 
cavernosa  (fig.  312),  injections  are  to  be  made  with  transparent 
blue  or  red  gelatine  fluid,  and  the  preparation  somewhat  strongly 
hardened.  The  lymphatics  of  the  glans  penis  are  to  be  in- 
jected by  the  puncturing  method  (Belajeff). 

We  have  finally  to  consider  the  semen  (sperm).        Q  a  || 
A  drop  of  evacuated  human  seminal  fluid  spread 
out  in  a  thin  layer,  without  any  further  addi- 
tion,  on   the   microscopic   slide,   shows,   with   a 
magnifying   power  of   about  400   diameters,   a 
number  of  peculiar  structures,  the  so-called  sper- 
matic   filaments,    spermatic     animalcula     (sper- 
matozoa,  zoosperms).      These    (fig.    313)  permit 
of   the  recognition  of   an  anterior  broader  flat- 1, 
tened  portion,  the  head   (a] ;    and  a  more  pos-      Fig.  sis. 

r  '  IT  matozoa     of      the 

tenor  long  filament,  with  a  relatively  thick  com-    sheep,     after 

J  Schweigger-Seidel. 

meiicing  portion,  the  so-called  middle-piece  (o) ;  ^ehfeac^i  ^t^d' 
and  a  terminal  filament  (c)  of  extreme  fineness. 

The  remarkable  movements  which  these  structures  present  in 
evacuated  living  semen  have  at  all  times  awakened  the  aston- 
ishment and  interest  of  the  observer ;  and,  in  fact,  a  wonderful 
appearance  is  presented  on  looking  down  into  this  confused 
mass  and  observing  the  spermatic  filaments  darting  wildly 
about.  A  closer  investigation  of  this  busy  multitude  shows 
that  the  individual  spermatic  element  makes  undulating  and 
whip-like  movements  of  the  filament,  and  is  thereby  pushed 
from  the  place. 

An  independent  change  of  position,  directed  towards  a  defi- 
nite object,  for  which  earlier  observers  mistook  the  phenomenon 
(and  in  harmony  therewith  declared  the  spermatic  elements  to 


558  SECTION   TWENTY-FIEST. 

be  animal  beings)  is,  however  in  no  wise  the  case.  If  the  phe- 
nomenon be  followed  throughout  a  longer  period,  it  will  be  seen 
how,  after  the  manner  of  the  nearly  related  ciliary  motions, 
the  movements  gradually  become  extinct ;  how  the  energy  of  the 
filamentary  movements  decreases  more  and  more,  and  thereby 
the  change  of  place  ceases ;  how  weaker  and  weaker  contortions 
of  the  filaments  are  then  to  be  noticed  in  the  spermatozoa, 
which  can  no  longer  move  from  the  place,  until  finally  the 
whole  becomes  quiet.  We  would,  in  addition,  repeat  here  a  re- 
mark which  we  have  already  made ;  namely,  as  each  excursion 
appears  very  much  exaggerated  by  the  strong  objective  (p.  101), 
the  irregular  advance  of  the  spermatozoa  should  not  be  over- 
estimated. It  is  in  reality  but  very  slow. 

More  indifferent  fluids,  blood-serum,  lymph,  white  of  egg, 
iodine-serum,  solutions  of  sugar  (1060-1030  sp.  wt.),  urea  (10-5 
per  cent.),  neutral  salts  of  the  alkalies  (chloride  of  sodium,  one  per 
cent.),  and  earths  may  be  employed  as  media.  Pure  water  in- 
creases the  energy  of  the  movement  of  mammalial  spermatozoa, 
at  most  for  a  very  short  time,  to  lead  to  a  rapid  cessation,  where- 
by the  filamentous  extremity  bends  itself  into  the  form  of  a 
loop.  Everything,  on  the  contrary,  which  acts  chemically,  gen- 
erally arrests  the  movement  once  for  all.  Spermatozoa  which 
have  become  quiet  from  too  watery  media  may  frequently 
be  temporarily  restored  to  life  by  means  of  a  concentrated 
solution  (of  sugar,  chloride  of  sodium  or  albumen),  and  in- 
versely. As  011  the  motus  vibratorius,  so  also  on  the  movements 
of  the  spermatozoa  a  peculiarly  stimulating  effect  is  exerted  by 
dilute  solutions  of  the  alkalies  and  caustic  potash  of  1-5  per  cent. 
(Kolliker).  The  alkaline  fluids  of  the  body  therefore  also  main- 
tain the  vitality  of  the  spermatic  filaments  for  a  long  time.  In  a 
similar  manner  a  suitable  solution  of  sugar  with  0.1-0.05  per 
cent,  of  caustic  potash  also  acts  excellently.  Moreover,  accord- 
ing to  Montegazza,  human  spermatozoa  preserve  their  vitality 
and  capability  of  motion  within  the  broad  thermometric 
limits  of  from  —15  to  +47  degrees  of  the  centigrade  ther- 
mometer. 

The  origin  of  the  spermatozoa,  from  cells  which  are  formed 
by  the  metamorphosis  of  the  ordinary  glandular  epithelium  of 


SEXUAL    ORGANS.  559 

the  seminiferous  canals,  removes  all  doubt — if,  indeed,  such 
were  still  possible — concerning  the  nature  of  these  structures 
as  tissue-elements. 

For  the  investigation  of  this  method  of  origin  (the  details  of 
which  are,  however,  still  matters  of  controversy),  a  sexually  ma- 
ture mammalial  animal,  such  as  a  male  dog,  rabbit,  or  Guinea- 
pig,  is  to  be  selected,  and  the  contents  of  the  testicle  examined 
immediately ;  and,  in  consequence  of  the  extreme  alterability 
of  the  spermatic  cells,  with  indifferent  fluids.  Strong  magni- 
fying powers  will  be  necessary. 

•  The  relatively  resistant  substance  of  which  the  spermatic 
filaments  consist  readily  permits  of  their  being  preserved  dry 
as  cabinet  preparations,  and  also  of  being  softened  with  water 
from  dried  seminal  stains,  and  thus  recognized  with  the  micro- 
scope. 

From  the  great  importance  which  the  recognition  of  the 
latter  is  for  the  medical  jurist  (and  it  may  still  be  accomplished 
after  years),  the  simple  procedure  may  here  find  its  place. 

The  suspicious  portions  are  to  be  cut  from  the  body  or  bed 
linen,  and,  having  been  reduced  to  small  pieces,  placed  in  a 
watch-glass  or  glass  box,  with  the  addition  of  a  small  quantity 
of  water.  After  a  time,  a  quarter  or  half  hour,  during  which  the 
pieces  of  linen  have  been  several  times  stirred  about  in  the 
water  with  a  glass  rod,  this  fluid  is  to  be  examined,  and  then 
the  fluid  pressed  drop  by  drop  from  the  fragments  on  to  the 
microscopic  slide.  Any  spermatozoa  which  may  be  present 
will  thus  be  discovered  with  certainty,  and  there  is  scarcely  any 
possibility  of  mistaking  them. 


0ccti0n   twenty -0CC0U  ft* 

GROANS  OF    SENSE. 

1.  THE  human  skin  consists  of  the  epidermis,  the  corium,  and 
the  subcutaneous  cellular  tissue ;  the  latter  being  rich  in  fat. 
Numerous  nerves,  blood-vessels,  and  lymphatics  permeate  it ; 
innumerable  glands  lie  embedded  in  it ;  the  hairs  and  nails, 
finally,  constitute  special  organs.  All  these  have  already  been 
individually  mentioned  in  previous  sections,  so  that  we  can 
here  only  present  a  short  recapitulation  of  the  whole. 


*  Fig.  314.  Human  skin  in  transverse  section,  a,  superficial  layers  of  the  epidermis ;  &,  Malpighian 
rete  mucosum.  Beneath  the  latter  is  the  corium,  forming  the  papillee  above  at  c,  and  termina- 
ting below  in  the  subcutaneous  connective  tissue,  in  which  at  ft  aggregations  of  fat-cells  appear ; 
g,  sudoriparous  glands,  with  their  excretory  ducts  e  and  /;  d,  vessels ;  f,  nerves  with  tactile 
bodies. 

The  structure  of  the  skin  may  be  represented  by  fig.  314,  a 


OKGANS    OF   SENSE.  561 

vertical  section  of  the  same  from  the  point  of  the  finger.  The 
cornified  epidermis  appears  at  a  with  its  numerous  layers  of 
flattened  cells  ;  the  (punctated)  layer  beneath  it  (b)  represents 
the  so-called  Malpighian  rete  mucosum.  The  papillse  of  the 
cutis  appear  at  <?,  and  beneath  them  commences  the  superfi- 
cial extension  of  the  corium,  which  is  sometimes  thinner,  some- 
times thicker,  and  passes  into  the  subcutaneous  cellular  tissue 
without  any  sharp  line  of  demarcation.  Among  the  constitu- 
ents of  the  latter  we  perceive  the  coil-shaped  bodies  of  the 
so-called  sudoriparous  glands,  <?,  the  ascending  ducts  of  which 
may  be  recognized  at/*,  as  well  as  the  aggregations  of  fat-cells 
h.  A  similar  section  through  a  hairy  portion  of  the  integument 
would  present  us,  in  addition,  the  hairs,  with  their  follicles  and 
the  sebaceous  follicles. 

Such  preparations  IT  ay  be  obtained  in  various  ways  from  the 
freshest  possible  corpses.  We  can,  although  with  some  trouble, 
still  without  any  further  addition,  prepare  pretty  thin  sections, 
and  render  them  transparent  by  means  of  weak  alkaline  solu- 
tions. If  the  fluid  medium  is  of  a  proper  degree  of  concen- 
tration, we  then  obtain  a  satisfactory,  although  very  perishable 
preparation.  It  is  preferable,  however,  even  here,  to  previously 
give  the  object  a  greater  degree  of  firmness  by  means  of  artifi- 
cial hardening.  The  drying  method  as  well  as  (which  I  prefer) 
the  immersion  in  absolute  alcohol  accomplishes  this  purpose. 
Many  views  will  be  obtained  in  a  better  form  if  boiling  in 
vinegar  precedes  the  drying,  or  a  precursory  immersion  in 
pyroligneous  acid,  after  which  the  object  is  placed  in  alcohol. 
A  prolonged  maceration  with  pyroligneous  acid  is  also  not  bad. 
Chromic  acid  has  not  presented  me  any  advantage  over  alcohol 
for  the  skin. 

Tingeing  with  aniline  blue,  and  especially  with  carmine  and 
subsequent  washing  in  very  dilute  acetic  acid,  is  excellent.  Such 
a  section  from  an  injected  portion  of  the  skin,  tinged  with  car- 
mine and  deprived  of  its  water  by  means  of  alcohol,  affords  a 
very  handsome  review  preparation  when  mounted  in  Canada 
balsam. 

To  enter  here  into  the  methods  of  examining  the  epidermis 

would  be  superfluous,  as  the  essentials  have  already  been  men- 
36 


562  SECTION   TWENTY-SECOND. 

tioned  at  pages  261  and  262,  and  the  peculiar  surfaces  of  the 
younger  cells  discussed.  The  nails  (p.  264)  and  hairs  (p.  265) 
have  likewise  been  treated  of  in  the  same  section. 

Fine  sections  of  dried  preparations,  or  those  hardened  in 
alcohol,  with  the  addition  of  acetic  acid,  serve  for  the  discovery 
of  the  elastic  fibres,  as  well  as  the  connective-tissue  corpuscles 
of  the  corium.  A  longer  immersion  in  undiluted  glycerine, 
by  rendering  the  connective-tissue  bundles  extremely  transpa- 
rent, permits  us  to  see  the  elastic  elements. 

The  same  methods  are  also  used  for  the  recognition  of  the 
sudoriparous  glands  and  sebaceous  follicles.  It  is  well,  however, 
not  to  select  too  thin  sections.  The  former  gland-formation, 
which  attains  to  gigantic  dimensions  beneath  the  skin,  of  the 
axilla,  may  be  readily  isolated  in  this  place  in  a  fresh  condition, 
and,  with  the  employment  of  the  familiar  methods,  the  structure 
of  the  walls  and  the  nature  of  the  cells  may  be  examined. 

Surface  sections  are  of  relatively  less  frequent  necessity. 
Made  through  the  upper  portion  of  the  epidermis,  however, 
they  are  of  importance  for  the  ducts  of  the  sudoriparous  glands, 
and  laid  deeper  on  the  border  of  the  former  towards  the 
corium,  for  the  study  of  the  papillae. 

The  primary  examination  of  the  sebaceous  follicles  may  be 
made  on  the  labia  majora,  likewise  on  the  skin  of  the  scrotum, 
by  picking  fine  sections  with  the  needles  and  employing  acetic 
acid.     Good  views  may  likewise  be  ob- 
tained, where  the  gland-cells  are  not  to  be 
preserved,  by  means  of  dilute  alkaline 
solutions.      The    dried    integument  of 
other  portions  of  the  body,  by  similar 
treatment,  also  shows  the  organs  in  the 
vicinity  of    the  hair-follicles.      Prepa- 
ratory boiling  in  vinegar  affords  a  good 
accessory  for  such  skin.      If  it  is  pro- 
posed to  examine  the  cells  and  the  re- 
foiiicie.  maiiiing  contents  of  the  sebaceous  folli- 
euSS^cles,the  skin  is,  according  to  Kolliker, 
to   be   previously  softened ;  then,  with 
the  epidermis,  the   hairs,  with  their  root-sheaths  and  the  cell 


ORGANS    OF    SENSE.  563 

masses  of  the  sebaceous  follicles,  are  often  rendered  very  finely 
prominent. 

The  blood-vessels  of  the  skin  are  to  be  examined  on  fine  ver- 
tical and  horizontal  sections  of  transparently  injected  organs. 
In  the  papillae,  at  the  point  of  the  finger,  an  extensive  natural 
injection  is  frequently  met  with,  so  that  the  transverse  section 
of  the  dried  skin,  by  the  addition  of  a  30  to  40  per  cent,  solution 
of  potash,  affords  very  handsome  views  of  the  vascular  loops. 

The  puncturing  method  serves  for  injecting  the  lymphatic 
passages  which  are  likewise  only  enclosed  by  connective  tissue. 
These  consist,  for  the  most  part,  of  a  double  horizontal  reticu- 
lurn  ;  a  deeper  one  with  wider  passages,  and  a  superficial  one 
with  narrower  canals.  Central  canals,  with  csecal  terminations, 
pass  from  the  latter  into  the  papillae  (Teichmann). 

For  the  study  of  the  muscular  tissue  of  the  skin,  the  tinge- 
ing  with  carmine  and  subsequent  treatment  with  acetic  acid, 
the  already  frequently  mentioned  double  tingeing  of  Schwarz, 
and  the  application  of  the  chloride  of  palladium  (I.  Neumann) 
is  to  be  recommended. 

Concerning  the  cutaneous  nerves,  we  would  first  refer  to  what 
was  mentioned  at  page,  369  about  the  tactile  bodies.  For  the 
study  of  these  elements  in  other  localities,  the  same  methods, 
the  treatment  of  thin  sections  from  the  fresh  or  dried  skin,  with 
.acetic  acid  and  alkalies,  and  furthermore  with  Muller's  fluid  or 
chloride  of  gold,  are  to  be  taken  into  consideration. 

The  Pacinian  corpuscles,  which,  together  with  terminal  knobs, 
also  occur  on  the  external  genitals  of  both  sexes  (Krause, 
Schweigger-Seidel),  are  to  be  examined  by  the  methods  cus- 
tomary for  these  structures. 

Peculiar  organs  nearly  related  to  the  terminal  knobs  were 
met  with  by  Krause  on  the  sensible  nerves  of  the  penis  and 
clitoris.  These,  the  "  genital  nerve-corpuscles,"  are  embedded 
in  the  corium  and  mucous  membrane  proper  (not  in  the 
papillae),  and  differ  from  the  ordinary  terminal  knobs  by  their 
more  considerable  dimensions  and  more  irregular  forms.  For 
their  examination,  the  discoverer  recommends:  firstly,  quite 
fresh,  when  possible  still  warm,  preparations  without  any  media ; 
then  injections,  and  an  immersion  in  3  per  cent,  acetic  acid. 


564  SECTION    TWENTY-SECOND. 

More  recently,  in  other  portions  of  the  integument,  fine,  non- 
medullated  nerve-fibres  are  said  to  have  been  seen  to  terminate 
with  button-shaped  swellings  between  the  cells  of  the  Malpi- 
ghian  rete  mucosum  (Langerhans).  The  treatment  of  the  fresh- 
est possible  thin  sections  with  chloride  of  gold  has  been  recom- 
mended for  their  recognition. 

The  embryos  of  man  and  the  mammalial  animals,  hardened 
in  chromic  acid,  are  used  for  the  foetal  skin.  On  small  foetuses 
the  latter  generally  separates  very  readily,  and  is  to  be  examined 
on  surface  sections  with  glycerine,  whereby  a  conservative  tinge- 
ing  with  carmine  renders  good  service.  With  older  embryos 
fine  vertical  sections  are  to  be  made  with  a  razor.  It  is  rela- 
tively easy,  on  such,  to  see  the  first  rudiments  of  the  sudoripa- 
rous glands  and  hairs,  and  also  on  the  latter  the  sebaceous  folli- 
cles, and  to  follow  their  further  development. 

The  pathological  changes  of  a  part  so  complicated  in  its 
structure  as  the  human  integument  are  of  a  very  manifold 
nature.  A  few,  such  as  are  connected  with  the  epidermis,  have 
been  already  mentioned  (p.  265).  Inflammatory  conditions 
show  sometimes  an  implication  of  the  whole  skin,  sometimes  of 
only  the  superficial  portions.  Extensive  emigrations  of  color- 
less blood-corpuscles  occur  there  (Yolkmann  and  Steudener). 
Desquamations  of  entire  layers  of  epidermis  (scarlatina),  local 
separations  of  the  horny  layer  from  the  Malpighian  stratum, 
by  collections  of  a  fluid  containing  pus-cells,  occur  as  a  result 
of  this  vascular  congestion. 

The  numerous  diseases  of  the  skin  affect  sometimes  the  epi- 
thelial, sometimes  the  connective-tissue  portion,  sometimes  both 
at  once. 

Elephantiasis  shows  a  more  extended  and  enormous  hyper- 
trophy of  the  corium  and  of  the  subcutaneous  cellular  tissue. 
Local  proliferations  of  the  tactile  papillae  of  the  skin  are  pre- 
sented by  the  warts  and  condylomata,  whereby  dilatations  and 
enlargements  of  the  capillaries  are  met  with.  The  vascular 
nsevi  and  telangiectasia  in  general  form  more  extended  super- 
ficial occurrences  of  the  latter  kind.  Follicular  tumors  and 
cysts,  of  frequent  occurrence  in  the  skin,  proceed  undoubtedly 
in  many  cases  from  dilatations  and  degenerations  of  the  hair- sacs 


OF  SE^SE.  565 

and  their  sebaceous  follicles.  These  frequently  present  the  so- 
called  atheromata ;  that  is,  the  follicle,  lined  with  a  pavement 
epithelium,  contains  a  grit-like  pulpaceous  mass,  in  which  the 
microscope  enables  us  to  recognize  exfoliated  epithelial  cells, 
fat-molecules,  and  crystals  of  cholesterine. 

The  maggot-pimples  or  comedones  present  slighter  metamor- 
phoses of  the  sebaceous  follicles  and  hair-sacs,  produced  by 
accumulated  secretions.  If  this  accumulation  is  confined  to  the 
sebaceous  follicles  (to  be  explained  by  impeded  evacuation), 
hordeolum  or  miliuin  is  produced.  The  degeneration  of  the 
hair-sacs  is  accompanied  by  that  of  the  respective  sebaceous 
follicles.* 

The  number  of  vegetable  and  animal  parasites'  found  in  and 
on  the  human  skin  is  a  considerable  one.  Many  of  these  con- 
stitute quite  indifferent  phenomena ;  others  cause  appreciable 
effects,  and  become  causes  of  diseases,  the  appreciation  of  which 
dates  from  the  discovery  of  these  structures  by  means  of  the 
microscope,  and  which  appear  in  part  on  and  in  the  hairs,  in 
part  on  the  horny  layer  of  the  epidermis,  partly  also  in  the  nails 
(though  the  nail  fungi  require  further  investigation). 

Among  the  epiphytes  or  vegetable  parasites  we  will  next 
mention  the  Tricophyton  tonsurans  of  Malmsten.  It  leads  to 
the  destruction  of  the  hairs  of  the  head  in  the  form  of  rounded 
patches  (herpes  tonsurans).  One  finds  only  spores  of  about 
0.0022'",  or  also  rows  of  the  same.  These  first  develop  in  the 
root  of  the  hair,  then  in  the  shaft,  which  it  splits  extensively, 
so  that  in  consequence  the  hair  breaks  oft  at  about  a  line  beyond 
its  exit ;  the  root  and  shaft  of  the  hair  are  likewise  destroyed. 
The  systematic  position  of  the  Tricophyton  tonsurans  is  still  a 
matter  of  controversy. 

Another  vegetable  parasite  of  the  hairs  of  the  human  head,  the 
Microsporon  Audouini  of  Gruby,  which  causes  the  porrigo  de- 
calvans,  behaves  in  a  similar  manner.  It  consists  of  rounded 
and  oval  spores  (of  0.0004-0.0022'")  and  a  network  of  curved 
undulating  filaments.  These  develop  externally  on  the  shaft 

*  For  more  particular  information  concerning  the  pathological  changes  of 
our  organ,  we  would  refer  to  I.  Neumann's  beautiful  text-book  on  skin 


566  SECTION   TWENTY-SECOND. 

of  the  hair,  and  occur  in  such  numbers  around  the  portion  of 
hair  which  projects  from  the  skin  that  it  becomes  destroyed, 
and  remnants  i  to  1  line  long  stand  out  from  the  skin. 

Another  fungus  of  the  same  name,  the  Microsporon  menta- 
grophytes  of  Robin,  grows  by  preference  in  the  follicles  of  the 
beard-hairs,  and  causes  an  inflammation  and  the  formation  of 
pus  around  the  hair-follicle — the  so-called  mentagra.  The 
microscope  shows  us  between  the  hair  sac  and  shaft  larger 
spores  and  filaments  than  in  the  previous  variety.  The  last 
two  varieties  are  uninvestigated  botanically.  Finally,  in  the 
Microsporon  furfur  of  Robin  groups  of  double-contoured  spores 
of  0.002"',  longitudinally  arranged  cells  and  branched  filaments 
of  0.0004-0.0002'"  in  diameter  may  be  recognized.  The  basis 
for  the  development  of  this  epiphyte  is,  however,  different ; 
namely,  the  horny  layer  of  the  epidermis,  where  it  causes 
yellowish  spots  and  a  furf uraceous  exfoliation  (pityriasis  versi- 
color). 

The  favus-fungus,  Achorion  Schoenleinii  of  Remak,  occurs 
principally  on  the  hairy  portions  of  the  skin  of  the  head,  and 
is  the  cause  of  the  scall,  porrigo  favosa — an  eruption  occurring 
mostly  during  childhood.  It  becomes  developed  first  in  the 
hair-sac,  where  it  surrounds  the  hair  and  grows  into  it ;  then, 
and  indeed  principally,  on  the  epidermis.  There  may  be  dis- 
tinguished, according  to  Robin,  the  0.001 3'"  broad  inarticulate 
filaments  of  the  mycelium,  the  somewhat  broader  unbranched, 
but  articulated  receptacula,  in  the  interior  of  which  series  of 
round  and  oval  spores,  0.0013-0.0026'"  in  size,  develop. 

t  The  nature  of  this  parasite  is  still  doubtful ;  possibly  it  is  a 
mould-fungus.  The  favus-scab  shows  under  the  microscope  a 
fine  granular  mass,  which  surrounds  the  fungus-substance 
proper.  Externally  this  consists  principally  of  the  mycelium, 
more  internally  of  the  receptacula,  and  quite  internally  of  the 
spores. 

The  examination  of  all  these  epiphytes  requires  in  general 
strong,  4-600-fold,  magnifying  powers.  For  the  study  of  the 
hair  fungi,  the  stumps  are  to  be  pulled  out  with  forceps  and 
rendered  transparent  by  means  of  pure  glycerine  or  oil  of 
turpentine.  With  the  fungi  growing  on  the  epidermoidal 


OKGANS    OF    SENSE.  567 

scales,  the  addition  of  alkalies,  the  dilute  solutions  of  potash 
and  soda  are  to  be  employed. 

Among  the  animal  parasites,  epizoa,  of  the  human  skin,  two 
may  here  be  mentioned,  both  mites  of  lower  organization ;  the 
hair-sac  mite,  Demodex  folliculorum,  Owen ;  and  the  itch-mite, 
Sarcoptes  hominis.  Both  live  in  the  skin  and  produce  quite 
different  effects.  While  the  first  animal  constitutes  a  quite  in- 
different parasite,  the  Sarcoptes  scabii  causes  the  familiar  compli- 
cation of  symptoms  known  under  the  name  of  the  itch  (scabies). 

The  Demodex   folliculorum  (fig.  316)  shows  a 
sometimes  more,  sometimes  less  elongated  body 
without  bristles  or  hairs.     On  the  fore  part  of 
the  body  in  the  young  creature  there  are  three, 
on  the  mature  animal  four  pairs  of  stump-like 
legs.     The  length  of  this  small  parasite  is  from 
•£--§• '" .     It  lives  generally  in  scanty  numbers  in 
the  excretory  ducts  of  the  sebaceous  follicles  and 
hair-sacs,  that  is,  the  space  between  the  hair-shaft 
and  the  root-sheath,  and  deposits  its  eggs  in  its 
dwelling-place.     It  occurs  in  the  sebaceous  fol-       Fig  316.  Hair. 
licles  of  the  face,  and  with  especial  frequency  in     Sx  Miic^oS? 
those  of  the  nose.     If  the  respective  glands  of 
the  latter  locality  are  strongly  developed,  the  smegma  may  be 
squeezed  from  the  opening  by  pressure,  the  mass  spread  out  in 
water,  and  the  mites  examined.      "With  dead  bodies  vertical 
sections  of  the  skin  are  to  be  prepared. 

Not  to  be  confounded  with  the  hair-sac  mite  is  the  larger 
itch-mite.  This,  which  is  represented  very  much  enlarged  in 
our  fig.  317,  has  a  rather  broad,  oblong  body,  from  -|— J- '"  in 
length,  covered  with  hairs  and  bristles.  The  first  two  pairs  of 
legs  are  placed  very  far  in  front ;  they  are  short,  and  with  a 
stalked  sucker.  After  a  considerable  interval  follow  the  last 
two  pairs  of  stump-like  legs,  which  terminate  in  long  bristles. 
The  ovum,  which  is  not  unfrequently  found  in  the  body  of  the 
female  animal,  is  (as  also  in  the  Demodex)  of  considerable  size, 
and  the  young  animal  is  likewise  six-footed. 

The  itch-mite  most  frequently  infests  the  human  skin  between 
the  fingers  and  on  their  inner  surfaces;  they  may,  however, 


568 


SECTION    TWENTY-SECOND. 


occur  on  all  parts  of  the  body.  It  penetrates  beneath  the 
epidermis,  and  forms  beneath  the  same  a  serpentine  passage, 
which  appears  brown  from  the  faeces  of  the  animal.  The 
animal  is  met  with  as  a  small  white  point  at  one  end  of  this 


Tig.  317.     The  itch-mite,  Sarcoptes  hominis,  from  a  photograph. 

To  obtain  the  mite  for  microscopic  examination  (which  does 
not  require  a  strong  magnifying  power),  the  passage  is  to  be 
slit  up  with  a  cataract-needle,  and  the  white  point  lifted  out 
on  the  point  of  the  needle.  For  a  more  accurate  study,  the 
portion  of  skin  which  contains  the  acarus  is  to  be  made  into 
a  fold,  and  this — epidermis  and  upper  portion  of  cutis — removed 
with  a  curved  scissors.  Spread  out  on  the  microscopic  slide, 
the  preparation  is  to  be  allowed  to  dry  gradually,  and  then 


ORGANS    OF    SENSE. 


569 


rendered  transparent  by  means  of  oil  of  turpentine  or  Canada 
balsam.  A  longer  immersion  of  the  moist  piece  of  skin  in 
concentrated  glycerine  also  affords  the  necessary  degree  of 
transparency. 


Fig.  318.     From  the  lateral  gustatory  organ  of  the  rabbit.    The  gustatory  ledges  in  vertical 
section,  after  Engelmann. 

2.  The  organ  of  taste  has  already  been  discussed  in  describing 
the  organs  of  digestion  (p.  419) ;  so  that  we  may  refer  to  the 
same,  and  here  treat  only  of  the  manner  of  termination  of  the 
nerves  of  sense. 

Investigations  which  were  earlier 
instituted  on  the  human  and  mam- 
malial  tongues,  on  their  papillae 
fungiformes  and  circumvallatse,  in 
regard  to  the  distribution  of  the 
nerves,  yielded  an  unsatisfactory 
result,  and  showed  only  the  nerve- 
trunks  with  divisions  and  plexiform 
communications,  terminating  finally 
in  pale,  non-medullated  fibres. 
Terminal  knobs  were  described 
here  years  ago  by  Krause.  In  the 
circumvallated  papillae  of  man  and 
the  mammalia,  Loven  and  Schwalbe 
recently  discovered  peculiar  ter- 
minal apparatuses,  denoted  by  the 
name  of  the  "gustatory  buds." 
They  occur  especially  in  the 
lateral  walls  of  these  papillae,  but 
not  unfrequently  also  at  the  inner 
surfaces  of  the  surrounding  ledges 
of  mucous  membrane. 

Our  fig.  318,  a  transverse  section  through  the  lateral  gusta- 


Gustatory  bud  of  the 
2  a,  cover-cells;  2  &,  rod- 
cells  ;  2  c,  a  rod-cell  with  a  fine  ter- 
minal filament. 


570  SECTION   TWENTY-SECOND. 

tory  organ  at  the  root  of  the  tongue  of  the  rabbit,  discovered 
by  Engelmann  and  Wyss,  may  afford  us  a  primary  representa- 
tion of  this  terminal  apparatus  of  the  gustatory  nerves  em- 
bedded in  the  epithelium.  We  may  obtain  a  more  accurate 
appreciation  from  fig.  319. 

The  parietes  of  the  gustatory  bud  (1)  consist  of  flattened, 
lancet-shaped  cells  (2  a),  which  stand  perpendicularly  by  the  side 
of  each  other,  comparable  to  the  staves  of  a  barrel  or  the  sepal 
leaves  of  a  flower-bud.  These  are  the  "  cover-cells." 

The  pointed  portion  of  our  organ  perforates  the  epithelial 
covering.  Small  roundish  spaces  occur  here.  They  are  formed 
in  part  by  several  epidermis  cells,  in  part  only  by  twos,  or 
finally  even  by  a  single  one. 

In  the  interior  of  the  organ  appears  a  second  cell-formation, 
the  "  gustatory  cell  "  (2  b).  A  spindle-shaped  body,  as  we  see, 
extends  above  into  a  rod,  and  is  prolonged  below  to  a  thin 
branched  filament.  It  penetrates  into  the  tissue  of  the  mucous 
membrane.  At  the  summit  of  the  rod,  finally,  a  short  fine 
cilium  shows  itself. 

A  plexus  of  medullated  and  non-medullated  nerve-fibres  has 
been  met  with  beneath  the  gustatory  bud.  The  communication 
of  these  with  the  lower  filamentous  termination  of  the  gusta- 
tory cells  still  remains  to  be  proved. 

Even  earlier  they  succeeded  in  recognizing,  with  some  prob- 
ability, the  termination  and  the  terminal  structures  in  the 
frog's  tongue  (Shultze,  Key). 

Fungiform  papillae  stand  separated  over  the  tongue  of  the 
frog.  The  lateral  portions  of  these  projections  and  the  edges 
of  the  surfaces  are  covered  by  ordinary  cylindrical  epithelium. 
The  plateau  of  the  papillae  shows,  on  the  contrary,  surrounded 
by  ciliated  cylinders,  another  covering  of  non-ciliated  cells, 
which,  on  suitable  chromic  acid  preparations,  after  brushing  off 
the  ordinary  epithelium,  may  sometimes  be  brought  to  view 
sitting  like  a  crown  on  the  gustatory  papillae.  Between  these 
non-ciliated  cells  lie  other  structures,  spindle-shaped  cell-bodies, 
which  pass  upward  into  a  fine  rod,  terminating  at  the  surface 
of  the  epithelial  crown.  Downwards,  on  the  contrary,  it  runs 
out  into  a  very  fine  filament,  which,  with  certain  reagents, 


ORGANS    OF    SENSE.  571 

appears  varicose,  and  which  mnst  be  regarded  as  the  terminal 
branch  of  an  axis-cylinder  which  has  been  split  up  in  a  tuft- 
like  manner.  The  nerve-fibres,  therefore,  split  up  into  fine 
fibrillse,  pass  over  into  these  rod-bearing  gustatory  cells.  These 
statements  of  Schultze  and  Key  have,  however,  been  more  re- 
cently modified  by  Engelmann.  He  denies  this  connection  of 
the  nerve-fibres  with  the  "gustatory  cells,"  and  describes  a  third 
(hitherto  confounded  with  the  gustatory  cells)  structure,  the 
"  forked  cell,"  with  a  small  ellipsoid  body,  which  is  prolonged 
above  and  below  into  forked  processes.  The  central  processes 
of  the  forked  cells,  with  great  probability,  pass  over,  under 
further  division,  into  the  axis-cylinders  of  the  nerve-fibres.  Pos- 
sibly, however,  both  varieties  of  cells  are  of  a  nervous  nature. 

Engelmann  has  recently  collected  the  methods  of  investiga- 
tion. 

For  the  primary  examination,  the  dried  mammalial  tongue 
(appropriately  that  of  the  rabbit)  may  be  employed.  The  sec- 
tions are  to  be  softened  in  dilute  acetic  acid  and  glycerine. 
The  organ  may  also  be  hardened  for  a  day  in  osmic  acid  (0.5- 
1.5  per  cent.).  The  freezing  method  also  affords  good  results. 

For  the  study  of  the  finer  structure,  the  maceration  in 
iodine-serum  and  the  immersion  forv  several  days  in  chromic 
acid  (1-2  per  cent.)  to  which  an  equal  volume  of  glycerine 
may  be  added,  are  to  be  recommended.  Such  preparations 
must  then  be  subjected  to  a  very  careful  picking  under 
the  simple  microscope.  According  to  Engelm ami's  expe- 
rience, extremely  fine-pointed  glass  rods  are  superior  to  the 
finest  steel  needles.  Wyss  gives  the  preference  among  all 
methods  to  an  immersion  for  about  three  weeks  in  Muller's  fluid. 

Dried  tongues,  or  those  which  have  been  frozen  in  a  suitable 
manner,  serve  for  following  the  nerves.  Sections  obtained  by 
the  freezing  method  may  be  subsequently  treated  with  chloride 
of  gold  (0.1-0.5  per  cent.)  or  osmic  acid  (0.25-2  per  cent.).  The 
nerve  expansions  under  the  gustatory  nerve  became  distinct 
for  Schwalbe  after  a  maceration  for  several  days  in  chromic 
acid  (0.02  per  cent.)  or  bichromate  of  potash  (0.5—1  per  cent.). 
Wyss  made  use  of  the  gold  method. 

3.  Further  advanced,  especially  by  the  admirable  investiga- 


572  SECTION    TWENTY-SECOND. 

tions  of  M.  S  chul  tze,  is,  on  the  contrary,  our  knowledge  of  the 
organ  of  smell,  that  is,  of  the  manner  of  termination  of  the 
olfactory  nerve.  Before  we  consider  the  remarkable  structural 
conditions  of  this  locality,  however,  let  us  mention  the  other 
portions  of  the  organ  of  sense. 

ISTo  portion  of  either  of  the  chief  cavities,  except  the  upper- 
most parts,  participates  immediately  in  the  perception  of  smell, 
and  does  not  contain  any  fibres  of  the  specific  nerves,  but  only 
those  from  the  trigeminus,  the  terminations  of  which  are  at 
present  still  unknown. 

Disregarding  the  entrance  to  the  nose,  a  ciliated  epithelium 
is  found  as  a  covering  to  the  proper  nasal  fossae  and  the  ac- 
cessory sinuses.  The  mucous  membrane,  thinner  in  the  ac- 
cessory sinuses,  is,  in  its  submucous  connective  tissue,  firmly 
unitedi  with  the  bones,  so  that  it  constitutes  at  the  same  time  a 
periosteum.  In  the  proper  nasal  fossae  it  becomes  thicker,  and 
very  rich  in  blood-vessels  and  racemose  mucous  glands. 


£- 


E 

Fig.  320.  The  regio  ouactoria  of  the  fox  in  vertical  section.  Z?,  The  cylindrical  epithelium  of 
the  same,  or,  Stratum  of  the  nuclei ;  6,  of  the  olfactory  cells ;  c,  of  the  pigment.  A,  The  adjacent 
ordinary  ciliated  epithelium.  «.  The  boundary  between  them.  C,  Ordinary  racemose  mucous 
glands.  Z),  Bowman's  glands,  with  the  duct  d.  JE7,  Branch  of  the  olfactory  nerve.  /,  Ascending 
branch  with  further  divisions. 

The  particular  manner  in  which  these  parts,  as  well  as  the 
cartilage  and  bones  of  the  parietal  system,  are  to  be  investigated 
does  not  require  further  discussion. 

In  catarrhal  conditions  of  the  nasal  mucous  membrane  we 


OEGANS    OF    SENSE.  573 

see  at  first  an  extensive  exfoliation  of  the  ciliated  cells,  which 
are  met  with  in  the  mucus  coming  under  examination,  partly 
still  ciliated  (and  even  in  motion),  partly  without  cilise.  To- 
gether with  the  regularly  shaped  cylindrical  cells,  others  of  a 
more  irregular  and  more  rounded  form  are  met  with.  Large 
cellular  structures,  which  have  arisen  from  the  metamorphosis 
of  the  normal  epithelial  formation,  contain,  at  this  commencing 
period  of  the  nasal  catarrh,  in  addition  to  their  nucleus,  granu- 
lated lymphoid  cells  (mucous-  or  pus-corpuscles)  wThich  have 
penetrated  from  without.  Nearly  all  these  elements  soon  dis- 
appear, with  the  exception  of  the  last-mentioned  structures, 
which  are  met  with  in  enormous  quantities  in  the  thick  yellow- 
ish secretion  of  the  later  periods.  Phenomena  which  we  have 
previously  alluded  to  under  similar  irritated  conditions  of  the 
respiratory  organs  (p.  49Y)  and  of  the  urinary  bladder  (p.  527) 
also  repeat  themselves  here. 

As  was  said,  the  greater  portion  of  the  olfactory  region  does 
not  participate  immediately  in  the  perception  of  smell,  as  the 
termination  of  the  specific  nerve  of  sense  is  met  with  only  in  a 
limited  portion.  Such  places,  called  regiones  olfactorise  (fig. 
320),  occur  in  all  vertebrate  animals,  but  present  numerous  dif- 
ferences. While  the  walls  of  the  remaining  portion  of  the  ol- 
factory cavity  are  covered  with  ordinary  ciliated  cells  (A), 
there  appears,  as  a  covering  for  the  regio  olf actoria,  a  likewise 
unstratified,  but  non-ciliated  cylindrical  epithelium  of  a  pecu- 
liar kind  (Z?),  mingled  with  cells  terminating  in  rod-like  pro- 
cesses, similar  to  those  we  have  just  become  acquainted  with  in 
the  frog's  tongue.  The  signification  of  nervous  terminal  cells 
cannot  be  denied  to  these  structures,  although  the  continual 
transition  of  the  lower  varicose  terminal  fibre  into  the  fibrillse 
of  the  olfactory  nerve,  cannot  yet  be  demonstrated  with  cer- 
tainty (either  by  Schultze  or  others,  as  for  instance  C.  K. 
Hoffmann).  The  extraordinary  delicacy  and  decomposability 
of  the  tissue-elements  under  consideration  (which  can  only  be 
managed  by  macerating  and  preserving  fluids  of  a  definite 
composition),  render  it  appreciable  that  during  a  long  period 
the  microscopists  either  did  not  recognize  the  complicated 
structure  at  all,  or  interpreted  it  erroneously. 


574 


SECTION    TWENTY-SECOND. 


In  the  mammalia  and  in  man  the  regio  olfactoria  dis- 
tinguishes itself  from  the  remaining  nasal  mucous  membrane 
by  a  peculiar  color,  by  a  yellow  or  yellow-brown  tinge.  This 

proceeds  from  fine  pigment  mole- 
cules, which  are  embedded  partly  in 
the  bodies  of  the  non-ciliated  cylin- 
drical epithelial  cells,  partly  in  the 
cells  of  an  especial  gland-formation 
occurring  here.  Vertical  sections  of 
the  part  which  has  been  hardened 
in  strong  chromic  acid  serve  for 
the  primary  survey.  These  nucle- 
ated cylindrical  cells  (fig.  321,  1  a, 
2  a)  may  be  recognized  from  suit- 
able side  views.  They  send  fila- 
mentous processes  in  a  downward 
direction,  which  pass  into  commu- 
nication with  each  other  by  means 
of  branches,  and,  having  arrived  at 
the  margin  of  the  mucous  mem- 
brane, they  undergo  a  further  more 
Profuse  division>  so  that  they,  at 


^^jsfssissstis  least  in  p'aces>  pass  over  iuto  a 

&HX^£teS£^;S£;   reticulum  which    is  very  delicate 

of  man.    The  references  the  same,  only  Qnrl      /Uflfn/'mlf      tr>     imrlmMtanrl       anrl 

short  projections,  e,  occur  (as  artefacts)  ail<1     CUn^Ult      IO     UliaeiStaiia,     and 

on  the  rods.    3.  Fibres  of  the  olfactory  -arVii/'li  rvffpn  csnrpnrk  nnt  intr»  a   Irinrl 

nerve  from  the  dog;    at  a  dividing  into  WHICH  OIlCIl  bpredUb  (. 

of  homogeneous  lamella  (similar  to 

the  membrana  limitans  of  the  retina).  Between  these  cylindri- 
cal cells  are  noticed  in  considerable  numbers  the  so-called 
olfactory  cells  (fig.  321,  1  5,  and  2  5),  structures  which  are  anal- 
ogous to  the  gustatory  cells.  At  very  different  elevations 
between  the  epithelial  cells  lies  a  spindle-shaped  nucleated  cell- 
body  (1,  2,  5),  which  extends  upwards  into  a  fine  rod  (c),  and 
downwards  into  an  extremely  fine  varicose  filament  (d). 

The  end  of  the  rod  which  has  reached  the  surface  appears 
to  terminate  quite  naked  in  all  mamrnalial  animals  ;  small  and 
quite  short  styliform  projections  (2  e\  which  may  be  noticed  on 
it,  are  the  contents  which  have  swollen  out  from  the  effects  of 


ORGANS    OF    SENSE.  575 

reagents.  This  appendix  is  also  absent  in  fishes  which  smell  in 
water.  In  birds  and  amphibia,  which  smell  in  the  air,  on  the 
contrary,  quite  large  in  part,  extremely  long  cilise,  sometimes 
slightly,  sometimes  not  at  all  movable,  occasionally  single,  oc- 
casionally in  numbers,  appear  on  the  free  extremity  of  the  rod, 
so  that  the  surface  of  the  regio  olfactoria  is  surmounted  by  a 
regular  hair-forest  (fig.  321,  1  e). 

Seen  from  the  surface,  one  may  recognize  how  the  pigmented 
cylindrical  cells  are  surrounded  in  a  circular  manner  by  these 
rods ;  while  by  the  side  view  the  rods  are  to  be  perceived  be- 
tween the  cylinders,  as  well  as  stratified  in  a  deeper  position,  the 
spindle-shaped  cell-bodies  of  the  structures  with  which  we  are 
at  present  occupied. 

Very  fresh  cadavers  are  necessary  to  obtain  the  same  struc- 
tures, cylinder-  and  olfactory-cells,  in  man.  Particularly  worthy 
of  recommendation  for  this  purpose  are  the  bodies  of  new-born 
children.  In  the  adult,  where  the  numerous  nasal  catarrhs 
have  preceded,  the  sharp  difference  in  color  between  the  regio 
olfactoria  and  the  remaining  portion  of  the  nasal  mucous 
membrane  is,  for  the  most  part,  wanting,  and  the  textnral  pecu- 
liarities are  likewise,  as  a  rule,  not  so  accurately  demarcated 
as  in  the  mammalial  animal.  Otherwise,  entire  conformity 
prevails. 

Peculiar  glands  (fig.  320  J9),  intermediate  in  form  between 
simple  cylinders  and  racemose  glands,  and  called  "  Bowman's 
glands  "  by  Ivolliker,  in  honor  of  their  discoverer,  are  situated 
in  the  middle  portion  of  the  regio  olfactoria,  and  permeate  this 
remarkable  cell-stratum  with  their  narrowed  excretory  ducts. 
Their  bodies,  lying  in  the  connective  tissue,  have  no  membrana 
propria,  and  consist  of  those  yellow  or  yellow-brown  pigmented 
gland-cells  of  which  mention  has  just  been  made.  The  adja- 
cent mucous  membrane,  on  the  contrary,  shows  ordinary 
racemose  mucous  glands  (0).  Although  an  ordinary  ciliated 
epithelium  is  found  in  places  in  the  human  regio  olfactoria, 
yet  these  true  racemose  gland-formations  follow  immediately. 
Of  interest  is  the  circumstance  that  the  Bowman's  glands  occur 
in  all  the  higher  vertebrate  animals,  but  are  absent  in  fishes 
which  smell  in  the  water. 


576 


SECTION    TWENTY-SECOND. 


The  olfactory  nerve  (fig.  320  £)  presents  only  non-medullated 
elements  in  its  branches.  These  appear  at  first  as  pale  nucle- 
ated fibres,  quite  similar  to  those  which  we  meet  with  in  many 
sympathetic  nerves,  as,  for  instance,  in  those  of  the  spleen.  By 
suitable  treatment,  however,  one  succeeds  in  separating  the  ol- 
factory nerve-fibre  into  extremely  fine  fibrillse  enclosed  in 
homogeneous  sheaths  ;  it  is  therefore  a  primitive  bundle. 

The  finer  branches  of  the  olfactory  nerve  (fig.  320,  fg)  ascend 
between  the  glands  of  the  regio  olfactoria,  and  thus  arrive  at 
the  margin  of  the  epithelium.  Here  they 
divide  into  the  finest  filaments,  or  primitive 
fibrillse.  These,  quite  similar  to  the  pro- 
cesses of  the  olfactory  cells,  and  appearing 
varicose  under  the  same  conditions  as  those, 
permeate  the  fine  latticed  reticulum  formed 
by  the  spreading  of  the  processes  of  the  cyl- 
inder-cells, to  finally,  as  we  must  admit  and 
have  already  remarked,  become  united  with 
the  processes  of  the  olfactory  cells  (fig.  322).. 
In  his  excellent  monograph,  Schultze  has 
given  us  a  long  series  of  directions  for  the 
demonstration  and  investigation  of  these  ex- 
tremely subtile  textural  relations,  and  thereby 
made  an  extremely  important  contribution  to 
microscopic  technology. 

To  obtain  a  primary  view  of  the  cells  of  the 
regio  olfactoria  from  the  body  of  a  mamma- 
lial  animal  just  killed,  thin  sections  obtained 
with  the  scissors  may  be  placed  under  the 
microscope,  with  the  addition  of  the  most  in- 
different possible  fluid  media.  In  these  the 
olfactory  cell-rods  will  be  discovered  between 
the  non-ciliated  epithelial  cylinders  as  hyaline 
rods.  However,  even  with  the  employment 
of  vitreous  fluid,  one  will  soon  see  hyaline 
drops,  which  proceed  from  the  decomposing 
olfactory  cell-rods,  coming  out  over  the  mar- 
gin of  the  epithelial  surface,  a  decomposition  which  takes  place 


h-/ 


Fig.  322.  Probable  ter- 
mination of  the  olfactory 
nerve  in  the  pike  (after 
Schultze).  a,  Olfactory 
cells ;  &,  rods  ;  c,  lower 
varicose  filament ;  e,  ax- 
is-fibrillse  in  the  sheath 
/;  d,  spreading  out  of 

these ;  at wanting 

connection      with      the 
same  flbrillae  c. 


OEGANS    OF    SENSE.  577 

with  even  greater  rapidity  from  the  addition  of  water. 
Schultze  found  the  addition  of  a  not  too  watery  glycerine  use- 
ful. Fine  vertical  sections  of  organs,  hardened  in  stronger 
chromic  acid,  or  dried  and  softened  in  acidulated  water,  also 
fulfil  this  purpose. 

To  isolate  the  epithelial  structures  (and  this  separation  is 
more  difficult  to  accomplish  in  warm-blooded  vertebrates  than 
in  cold-blooded  ones),  the  employment  of  conservative  and 
macerating  fluids  is  necessary.  This  effect  is  rapidly  and 
thoroughly  obtained  by  the  use  of  the  30-40  per  cent,  solution 
of  potash,  or  one  of  soda  of  20-25  per  cent.  If  quite  fresh  pieces 
of  the  ethmoid  bone,  with  the  adherent  mucous  membrane,  be 
immersed  in  this,  and,  after  the  lapse  of  a  half  or  a  whole  hour, 
the  epithelium  be  scraped  off,  the  separation  may  be  accom- 
plished on  the  microscopic  slide.  With  weaker  solutions  one 
must  wait  two  or  three  hours.  The  well-preserved  cylinder- 
cells  and  rods,  a  portion  of  them  still  in  connection  with  the 
spindle-shaped  olfactory  cells,  may  then  be  readily  recognized, 
and  in  amphibia  and  Nbirds  even  the  olfactory  cilise ;  on  the 
contrary,  there  is  usually  nothing  preserved  of  the  descending 
fine  filamentous  processes  of  the  latter. 

To  obtain  a  surface  view,  the  epithelial  covering,  macerated 
in  a  solution  of  potash  or  treated  with  glycerine,  is  to  be  used. 
Better,  though  much  more  slowly,  commencing  (from  two  to 
three  days)  effects  may  be  obtained  by  maceration  in  a  very 
dilute  solution  of  chromic  acid  (whereby  the  immersed  portion 
should  not  be  too  small,  nor  the  quantity  of  fluid  too  great). 
0.05-0.03  per  cent,  solutions  are  to  be  recommended  for  the 
quite  fresh  mammalial  animal.  For  the  human  olfactory  organ, 
when  it  can  be  obtained,  about  twelve  hours  after  death, 
Schultze  employed  the  action  of  a  chromic  acid  solution  of 
0.05  per  cent,  for  from  one  to  three  days.  Cold-blooded  verte- 
brate animals  require  somewhat  stronger  solutions  than  the 
mammalia;  birds  somewhat  weaker  ones  (to  0.01  per  cent.). 
(The  division  of  the  bundles  of  the  olfactory  nerves  into  prim- 
itive fibrillse  may  also  be  accomplished  in  this  way.) 

The  extraordinary  advantage  which  such  solutions  present 
for  the  study  of  the  regio  olf actoria,  consists  in  rendering  visible 
37 


578  SECTION   TWENTY-SECOND. 

varicose  swellings  on  the  very  fine  lower  filamentous  processes 
of  the  olfactory  cells,  as  well  as  the  finest  terminal  fibrillse  of 
the  nerves  of  sense  (a  superiority  which  also  belongs  to  the 
reagent  for  analogous  textural  conditions  of  the  remaining 
higher  nerves  of  sense).  As  has  already  been  frequently  men- 
tioned, the  bichromate  of  potash  may  be  employed  instead  of 
chromic  acid ;  its  action  takes  place  slowly.  Schultze  em- 
ployed solutions  of  0.1-0.5  per  cent.,  and  obtained  the  desired 
preparations  after  1-6  days. 

The  Miiller's  fluid,  which  is,  as  I  found,  very  suitable  for  the 
examination  of  the  cochlea  when  diluted  with  water,  I  also 
recommended  years  ago  in  several  degrees  of  dilution.  Accord- 
ing to  Hoffmann's  experience,  diluted  with  an  equal  part  of 
water,  and  sometimes  acting  only  one  or  two  days  (frog),  some- 
times for  nearly  two  weeks  (mammalia),  it  in  fact  constitutes 
the  best  of  all  macerating  media. 

Schultze  has  discovered  and  recommended  still  other  simi- 
larly acting  fluids. 

The  concentrated  watery  solution  of  oxalic  acid  preserves  (p. 
133)  the  olfactory  cells,  their  rods  and  varicose  filaments  (but  not 
the  cylinder-cells)  quite  exquisitely  ;  and  one  has  the  great  ad- 
vantage of  not  being  too  dependent  upon  the  time,  so  that  the 
examination  may  be  made  even  after  a  few  hours,  and  also 
after  days.  The  connective  tissue  swells  in  it  and  becomes 
more  transparent,  while  albuminous  tissues  retain  their  sharp 
contours  and  become  somewhat  harder. 

Sulphuric  acid  in  a  condition  of  high  dilution,  in  medium  of 
0.6  per  cent.  (0.2-1  per  cent,  and  more),  also  preserves  the 
olfactory  cells  very  well,  and  still  more  diluted  it  renders  the 
filaments  varicose.  The  connective  tissue,  however,  does  not 
swell  in  it  as  in  the  previous  acid,  but  is  rendered  much  more 
beautiful  and  sharp.  Here  also  too  small  pieces  should  not  be 
taken,  and  the  preparation  is  to  be  tried  even  after  a  few  hours. 
The  immersed  pieces  keep  for  days  and  weeks  if  they  are  not 
ruined  by  the  formation  of  mould.  This  acid  is  less  praised 
by  Hoffmann. 

To  obtain  degrees  of  hardening  which  are  suitable  for  the 
preparation  of  thin  sections,  and  which  should  present  the 


OEGANS    OF    SENSE.  579 

arrangement  of  the  mucous  membrane,  the  glands  of  Bowman 
and  the  course  of  the  nerves,  one  may  employ,  together  with 
the  Mliller's  fluid,  higher  degrees  of  concentration  of  chromic 
acid  and  chromate  of  potash,  and  subsequently  examine  with 
glycerine,  acetic  acid,  etc.  Moleschott's  so-called  strong  acetic- 
acid  mixture  (p.  142)  has  also  been  especially  recommended  by 
Balogh. 

Strongly  hardened  objects,  as  well  as  the  preparations  of  the 
remaining  portions  of  the  nasal  mucous  membrane,  one  should 
attempt  to  mount  in  glycerine.  The  olfactory  cells  and  the 
cylindrical  epithelium  lying  betwen  them  may  be  still  more 
suitably  preserved  in  Muller's  fluid  diluted  with  an  equal  quan- 
tity of  water. 

4.  The  organ  of  vision,  from  its  greater  complication,  re- 
quires a  more  detailed  discussion. 

The  eyelids,  with  the  cutis  accompanying  them,  their  connec- 
tive-tissue so-called  tarsal  cartilage,  and  the  embedded  Meibo- 
mian  glands,  which  in  their  form  remind  one  of  those  of  Bow- 
man in  the  olfactor^  organ,  as  well  as  the  conjunctiva  of  their 
posterior  surface  and  of  the  eyeball,  together  with  the  epithelial 
covering  which  clothes  it,  do  not  require  discussion.  Their 
tissues  are  to  be  examined  in  accordance  with  previous  direc- 
tions. The  Meibomian  glands  may  be  recognized  with  facility, 
in  their  coarser  relations,  in  the  eyelids  of  small  mammalial  ani- 
mals rendered  transparent  by  means  of  alkalies  or  by  immersion 
in  vinegar ;  fine  sections  from  the  dried  organ  serve  for  the 
investigation  of  the  finer  structure.  The  lachrymal  glands  are 
to  be  examined  in  the  same  manner  as  other  racemose  glands. 

The  conjunctiva  of  the  eye  (frequently  a  lymphoid  infiltrated 
connective  tissue)  contains  throughout  the  entire  line  of  transi- 
tion numerous  racemose  mucous  glands,  while  in  the  conjunctiva 
of  the  eyeball  (the  portion  surrounding  the  cornea)  of  the  rumi- 
nantia,  coil-shaped  glands,  quite  similar  to  those  of  the  skin, 
have  been  discovered  (Manz).  Maceration  in  dilute  acetic  acid 
or  pyrol igneous  acid  will  make  them  readily  visible.  For  the 
recognition  of  the  peculiar  nerve  terminations  in  the  Krause's 
knobs  (fig.  223),  the  fresh,  still  warm  eye  of  one  of  our  slaughter- 
house animals  may  be  used.  The  conjunctiva  is  to  be  removed 


580 


SECTION    TWENTY-SECOND. 


with  rapidity,  but  with  the  utmost  caution,  and  searched  with 
low  powers  and  without  the  addition  of  any  medium.  The 
necessary  details  concerning  the  reagents  have  already  been 
mentioned  at  page  369. 

"We  have  also  previously  men- 
tioned (p.  366  and  fig.  184)  the  re- 
markable termination  of  very  fine 
nerve  fibrillse  in  the  epithelium  of 
the  conjunctiva. 

The  blood-vessels  of  the  conjunc- 
tiva present  nothing  remarkable. 
The  lymphatics  of  the  human  con- 
junctiva form  a  highly  developed 
network  of  passages  of  consider- 
able size  over  the  sclerotic,  which 
also  occupies  the  peripheral  portion 
of  the  cornea  for  about  one  milli- 
metre in  breadth,  and  consisting 
here  of  finer  canals  with  bow-like 
terminations  (Teichmann).  Among 
mammalial  animals  I  have  suc- 
ceeded in  injecting  such  canals  in 
the  calf. 

Interesting  phenomena  of  the 
conjunctiva  are  presented  by  the 
trachoma  glands,  as  they  have  been 
called :  lymphoid  follicles  very  similar  to  those  of  the  in- 
testinal canal,  and  quite  variable  in  number  and  arrangement.* 
The  injection  in  the  ox  (fig.  324)  shows  that  knotty  lymphatics 
(a)  of  considerable  size  run  towards  their  lower  surface,  and, 
after  the  loss  of  their  vascular  walls,  form  a  highly  developed 
network  of  lymphatic  canals  around  them,  from  which  finer 
reticular  canals  encircle  the  follicle  and  spread  themselves  out 
in  a  delicate  manner  (c)  in  the  lymphoid  stratum  uniting  the 
follicles  (b),  Their  most  superficial  portions,  that  is,  those 


Fig  323.  Terminal  knobs :  1,  from  the 
calf  ;  2,  from  man. 


*  According  to  the  statement  of  Blumberg,  our  structures  are  still  entirely 
absent  in  the  conjunctiva  of  quite  young  animals. 


OBGAtfS    OF    SENSE.  581 

turned  towards  the  epithelial  layer,  run  more  horizontally,  and 
send  off  fine  terminal  canals  which  present  quite  superficial 
csecal  terminations.  The  whole  is  enclosed  in  connective  tissue, 
and  the  whole  arrangement  is  related  in  the  most  intimate 
manner  to  that  of  a  Peyerian  plaque ;  only  the  blood-vessels 
of  the  follicles  are  here  less  abundant  and  less  regular.  f 


Fig.  324.    Trachoma  gland  of  the  ox,  with  injected  lymphatics,  in  vertical  section,    a,  submu- 
cous  lymphatic  vessel ;  c,  its  distribution  to  the  passages  of  the  follicle  6. 

The  eyes  of  younger  oxen  cr  older  calves,  and  cold-flowing 
mixtures  are  to  be  uked  for  injections,  which  should  be  made  in 
the  so-called  Bruch's  aggregation  of  the  trachoma  glands  of  the 
lower  eyelid.  The  other  aggregation  may,  however,  also  be 
very  readily  injected ;  and  furthermore,  the  injection  of  the 
blood-vessels  by  the  smaller  arteries  also  succeeds  without  great 
difficulty,  while  with  smaller  mammalial  animals  the  entire 
head  must  be  injected  from  the  aorta  with  colored  gelatine. 

The  procedure  is  difficult  in  man  and  many  other  mammalial 
animals.  The  preparations  are  to  be  hardened  in  alcohol  for 
examination. 

With  regard  to  the  eyeball  itself,  it  may  be  said  that  its 
examination  is  one  of  the  most  remunerative  labors  of  the 
microscopist ;  but  at  the  same  time,  however,  in  one  of  its  ele- 
ments (the  retina)  combined  with  the  greatest  difficulties.  One 
should  always  use  the  quite  fresh,  still  warm  eyes  of  the  larger 
slaughtering  animals,  especially  those  of  the  ox,  calf,  and  sheep, 
as  well  as  indifferent  fluid  media,  such  as  the  vitreous  and  aque- 
ous humors  which  are  always  at  hand.  If  the  eyes  have  been  re- 
moved with  a  little  care,  the  artery  may  be  readily  found  lying 


582  SECTION   TWENTY-SECOND. 

near  the  optic  nerve  and  employed  for  injecting  (the  injection 
of  the  human  eye  is  more  difficult  in  consequence  of  the 
smallness  of  the  artery).  Such  injections,  when  they  are  to  be 
followed  by  histological  investigations,  are  always  to  be  made 
with  cold-flowing  mixtures,  the  Prussian  blue  or  carmine. 
The  injection  of  an  eye  of  one  of  the  larger  animals,  after  the 
numerous  divided  vessels  have  once  been  ligated,  usually  suc- 
ceeds in  from  two  to  three  minutes.  Even  after  a  quarter  of 
an  hour  one  may  commence  with  the  dissection  and  examina- 
tion. The  system  of  the  uvea,  especially,  shows  many  things  in 
a  much  more  instructive  manner  than  in  the  injected  organ,  and 
the  unpigmented  tapetum  of  such  eyes  affords  a  further  advan- 
tage for  many  investigations.  Where  especial  reference  is  to 
be  made  to  injected  preparations,  inject  with  carmine  gelatine. 
The  eyes  of  the  smaller  mammalial  animals  are  to  be  injected 
from  the  aorta  simultaneously  with  and  under  the  same  pre- 
cautions as  the  brain  (p.  350).  "White  rabbits  afford  excellent 
objects.  The  eyeballs  of  this  animal,  divided  in  halves  and 
mounted  in  glass  cells  with  Canada  balsam,  which  have  been 
put  in  circulation  by  Thiersch,  may  be  recommended  as  true 
models  of  the  modern  injection  technique.  If  it  be  desired  to 
accomplish  a  double  injection,  Prussian  blue  is  to  be  first 
thrown  into  the  artery,  and  a  second  injection  of  carmine  gela- 
tine is  then  to  be  made  by  the  same  vessel.  Leber  has  recently 
instituted  excellent  studies  of  this  kind,  with  cold-flowing 
masses  and  the  use  of  the  constant  pressure. 

The  investigation  of  such  fresh  eyes  requires  in  part  trans- 
verse sections,  as  of  the  cornea  and  sclerotic  ;  but  generally, 
however,  a  dissection  of  the  membranous  structures.  These 
may  be  first  reviewed  unpicked  with  vitreous  fluid,  or  the  ad- 
dition of  reagents,  and  hereby  folds  which  are  artificially  made 
are  for  the  most  part  very  instructive,  or  they  are  to  be  divided 
with  fine  needles.  Much  may  be  recognized  in  such  a  manner 
concerning  the  texture  of  the  eyeball,  and  even  of  the  retina. 
In  this  way  all  the  former  (and  in  part  adequate)  knowledge  of 
the  same  was  obtained  ;  and  even  with  the  employment  of  other 
more  modern  methods,  the  criterion  of  the  fresh  condition  can 
never  be  dispensed  with.  Certain  elements  of  the  eyeball,  on 


ORGANS    OF    SENSE.  583 

the  contrary,  are  in  part  so  transparent,  in  part  so  delicate  and 
soft,  that  hardening  (and  darkening)  methods  of  treatment  be- 
come indispensable.  Many  structural  conditions,  the  termina- 
tion of  this  and  that  structure,  the  relations  of  continuity  of  the 
one  with  the  other,  etc.,  can  only  be  ascertained  with  adequate 
certainty  from  such  preparations.  Those  two  methods  which 
we  have  already  had  to  mention  in  connection  with  so  many  or- 
gans, the  drying  and  the  hardening  by  means  of  reagents,  are 
also  employed  here.  For  the  former  purpose  the  eyeball  is  to 
be  divided  at  the  equator,  and  the  vitreous  body  (generally  also 
the  lens)  removed.  Both  segments  should  be  spread  over  the 
surface  of  cork,  cut  into  semispheres.  For  hardening,  use  either 
absolute  alcohol  or — what  is  far  more  customary — chromic  acid 
(0.5-0.2  per  cent.)  and  chromate  of  potash.  The  bulb  may  be 
either  divided,  only  cut  open,  or  even  left  entirely  unopened  (in 
which  case  a  stronger  solution  of  the  hardening  medium  is  to 
be  selected).  The  M  tiller's  eye-fluid  (p.  139)  is  very  excellently 
adapted  for  hardening  the  unopened  immersed  eyeball.  It  is 
necessary,  it  is  true,  to  wait  two  or  three  weeks  for  the  adequate 
effect ;  but  the  eye  may  also  be  allowed  to  lie  in  it  for  months 
and  even  years  without  any  harm,  and  with  this  accessory 
very  handsome  specimens  of  most  parts  of  the  bulb  may  be  ob- 
tained. The  mixture  has  therefore,  with  propriety,  come  more 
and  more  into  use  among  ophthalmologists.  If  a  weaker  action 
is  aimed  at,  it  is  to  be  diluted  with  water ;  to  obtain  stronger 
hardening,  a  little  chromic  acid  is  to  be  added.  Injected  eyes 
may  also  be  hardened  in  this  manner,  though  the  color  suffers 
somewhat.  If  it  be  desired  to  avoid  this,  employ  cold-flowing 
baryta  masses  (p.  185). 

Let  us  next  examine  the  methods  for  investigating  the  capsu- 
lar  system,  the  cornea  and  sclerotic. 

The  structure  of  the  cornea  (fig.  325),  with  both  its  epithelial 
layers,  the  stratified  of  the  anterior  (d),  and  the  simple  cell-cov- 
ering of  the  posterior  surface  (e\  with  the  two  hyaline  boundary 
layers  of  the  so-called  lamina  elastica  anterior  (£),  and  the  mem- 
brane of  Descernet  (c)  appearing  under  them,  as  well  as  the 
ordinary  corneal  substance  (a)  and  their  cellular  elements,  have 
been  so  frequently  treated  of  and  discussed  of  late  that  it  would 


584 


SECTION   TWENTY-SECOND. 


be  superfluous  to  enter  further  into  the  textural  relations  in  ques- 
tion. The  best  descriptions  of  the  cornea  are  those  of  His, 
Kiihne,  Engelmann,  and  Schweigger-Seidel. 


Fig.  325.  The  cornea  of  the  new-born  in  vertical  section  (but  considerably  shortened),  a,  Cor- 
neal  tissue ;  ft,  anterior,  c,  posterior  hyaline  layer ;  d,  stratified  pavement  epithelium ;  e,  simple 
epithelial  layer. 

"With  regard  to  the  methods  of  examination,  it  is  to  be  said 
that  the  quite  fresh  transparent  cornea  of  an  animal  which 
has  just  been  killed  may  be  employed.  It  may  be  cut  through 
from  the  side,  or,  although  with  some  trouble,  fine  vertical  and 
surface  sections  may  be  removed  from  it  with  the  aid  of  a 
very  sharp  razor.  Humor  aqueus  serves  for  moistening,  and 
a  moist  chamber  (p.  103)  for  the  preservation  of  the  object. 


OEGANS    OF    SENSE.  585 

For  the  recognition  of  the  effete  corneal  corpuscles  and  their 
contents,  use  very  weak  acetic  acid,  or  extremely  dilute  chromic 
acid  solutions  of  0.01  per  cent.  Here,  however,  as  with  all 
the  following  methods,  artificial  (and  often  very  considerable) 
alterations  are  not  to  be  avoided,  as  the  interstitial  substance 
swells  and  the  cells  usually  shrink. 

Drying  is  also  useful.  Yery  thin  sections,  either  only 
softened  in  weakly  acidulated  water,  or  first  tinged  in  carmine 
and  then  washed  out  with  diluted  acetic  acid,  afford  good 
review  specimens  (fig.  325). 

His,  a  meritorious  investigator  of  our  membrane,  recom- 
mends first  the  acetic  acid  with  iodine  staining,  to  cause  the 
corneal  cells  to  appear  through  the  transparent  interstitial 
substance. 

According  to  him,  however,  the  immersion  in  purified  pyro- 
ligneous  acid,  diluted  with  an  equal  volume  of  water,  or  even 
more,  constitutes  a  main  accessory.  The  cells,  with  more  cloudy 
contents,  then  appear  through  the  somewhat  swollen,  more 
transparent  interstitial  substance.  The  hardening  property 
which,  as  is  known,  is  also  associated  with  the  distending 
power  of  the  pyroligneous  acid,  is  also  of  great  worth  here 
for  rendering  fine  transverse  sections  feasible.  These  may  be 
vertical,  exactly  similar  to  those  from  the  dried  object,  and 
then  (which  is  not  possible  with  the  latter  material)  the  very 
much  more  instructive  horizontal  sections.  Entire  corneas 
may  also  be  preserved  for  years  in  pyroligneous  acid. 

Another  mixture,  mentioned  by  Remak,  consisting  of  dilute 
pyroligneous  acid,  watery  alcohol,  and  a  weak  solution  of 
sulphate  of  copper,  causes  less  swelling,  but  otherwise  yields 
quite  similar  appearances.  Chromic  acid  presents  no  advan- 
tage over  pyroligneous  acid. 

Other  reagents,  such  as  concentrated  chromic  acid,  Mutter's 
fluid,  saturated  solutions  of  sugar,  dilute  alcohol  of  50  per 
cent.,  and  Merkel's  chromic  acid  and  chloride  of  platinum 
mixture  (p.  140),  exert  a  shrinking  effect  on  the  interstitial 
substance,  and  have  been  recommended  for  demonstrating  a 
fibrillary  structure  of  the  corneal  tissue. 

Frequent  use  has  also  been  made  of  the  silver  method  in  the 


586  SECTION   TWENTY-SECOND. 

examination  of  the  cornea  and  a  reticulum  of  star-shaped  figures, 
which  appear  sometimes  bright  out  of  a  darker  basis  substance, 
sometimes  dark  with  brighter  surroundings,  pronounced  to  be 
the  network  of  corneal  cells  (His). 

Much  more  certain  views  are  afforded,  however,  by  the 
cornea  treated  with  chloride  of  gold.  The  cellular  elements 
and  the  nerves  are  alone  colored,  and  the  former  preserve  all 
their  details.  This  reagent  is  here  of  the  first  rank,  as  Cohn- 
heim  rightly  remarked.  Its  hardening  property  permits  of 
the  preparation  of  vertical  and  surface  sections. 

Frequent  use  has  more  recently  been  made  of  the  most 
uninjured  possible  cornea  of  the  frog  (Ktlhne,  Kecklinghausen, 
Engelmann).  One  should  proceed  here  in  accordance  with  the 
directions  given  at  page  249.  The  cornea  is  to  be  examined 
with  its  posterior  surface  turned  upwards,  preferably  without 
any  covering  glass  and  with  an  immersion  system. 

At  first  one  sees  next  to  nothing  in  the  hyaline  transparent 
tissue ;  at  most,  striations  of  the  same  and  traces  of  the  corneal 
nerves.  After  a  more  close  examination  one  finds  small 
isolated,  dull  glistening  structures  of  a  sometimes  rounded, 
sometimes  elongated,  occasionally  crooked  form.  The  observer 
convinces  himself  that  these  bodies  stretch  out  delicate  pro- 
cesses and  draw  others  in ;  in  short,  constantly  change  their 
form  and  location.  These  are  the  already  mentioned  (p.  250) 
wandering  cells  of  Recklinghausen. 

If  we  wait  half  an  hour  longer,  the  corneal  corpuscles  begin 
to  stand  out  from  the  tissue  in  the  form  of  extremely  pale, 
polygonal  appearing  dull  spots.  If  about  another  half-hour 
be  allowed  to  pass,  our  corneal  corpuscles  become  more  distinct ; 
the  dull  spots  are  connected  with  each  other  by  radiated  pro- 
cesses ;  the  reticulum  of  cells  is  visible.  Nuclei  are  not  yet  to 
be  discerned  in  the  latter.  Kiihne  asserts  that  he  has  con- 
vinced himself  of  a  vital  contractility  in  these  stellate  cells. 
Engelmann  saw  no  trace  of  this  in  his  re-examination.  The 
change  of  form  and  location  of  the  wandering  cells  is,  on  the 
other  hand,  to  be  observed  now  as  before  (and  with  proper 
treatment  for  a  long  time  yet). 

"We  will  here  mention  still  another  interesting  and  important 


OEGANS    OF    SENSE.  587 

observation  concerning  the  latter  cell-formation.  We  have  al- 
ready (p.  102)  alluded  to  the  reception  of  small  granules  into 
the  interior  of  such  amoeboid  structures.  If  a  small  incision  be 
made  at  the  sclerotic  border  of  the  cornea  of  a  living  frog,  and 
granules  of  cinnabar  or  carmine  be  rubbed  into  it,  the  cornea, 
isolated  after  twelve  hours  or  more,  will  show  a  number  of 
these  cells  with  the  colored  molecules  in  their  interior,  occa- 
sionally considerably  removed  from  the  wound,  wandering 
through  the  tissue. 

Concerning  the  two  hyaline  limiting  layers  of  the  cornea,  it 
may  be  stated  that  the  membrane  of  Descemet  may  be  readily 
isolated  by  scraping  with  the  firm  pressure  of  a  scalpel.  An 
incomplete  separation  of  the  membrana  elastica  anterior  from 
the  deeper  corneal  tissue  may  be  accomplished  by  maceration 
in  muriatic  acid. 

Dried  sections  mounted  in  Canada  balsam  are  to  be  employed 
for  recognizing  the  double  refraction  of  the  interstitial  sub- 

O  O 

stance. 

The  organ  of  smaller  embryos  affords  handsome  preparations 
for  the  cells  and  interstitial  substance.  His  recommends  about 
two-inch  foetuses  of  the  cow  and  hog. 

We  have  already  discussed  the  examination  of  the  nerves  of 
the  cornea  in  a  previous  section  of  our  work  (p.  366),  so  that  we 
must  refer  to  the  details  there  presented. 

The  blood-vessels  occupy  only  the  peripheral  portion  of  the 
organ  iu  the  adult,  as  we  learn  from  artificial  and  natural  in- 
jections. 

The  magnificent  transparency  of  the  so  accessible  cornea 
renders  it  more  than  any  other  structure  appropriate  for  artifi- 
cial inflammatory  irritations,  and  the  study  of  the  tissue-meta- 
morphoses which  take  place  thereby.  It  is  therefore  frequently 
employed  for  such  investigations,  and  the  facts  obtained  inter- 
preted in  accordance  with  the  prevailing  pathological  views. 
While  years  ago  the  profound  work  of  His  appeared  to  lend  an 
important  support  to  Virchow's  theory  concerning  the  partici- 
pation of  the  connective-tissue  corpuscles  in  the  inflammatory 
process  ;  at  the  present  time  the  case  is  entirely  reversed,  and 
the  cornea  has  become  a  favorite  object  of  study  for  demon- 


588  SECTION   TWENTY-SECOND. 

strating  the  correctness  of  the  Waller-Cohnheim  theory  of  the 
immigration  of  lymphoid  cells.  The  doubters  have  also  re- 
sorted to  this  field. 

To  induce  the  inflammation  of  the  cornea  (keratitis),  our 
structure  is  to  be  irritated  by  the  application  of  tincture  of  can- 
tharides,  a  stick  of  nitrate  of  silver,  or  by  the  insertion  of 
threads  and  silver  wires. 

The  desired  inflammation  is  obtained  in  rabbits  after  24 
hours,  in  summer  frogs  after  2-3  days,  but  only  after  double 
this  time  in  hibernating  frogs. 

If  cinnabar,  carmine,  or,  still  better,  aniline  Line  suspended  in 
water  has  been  injected  with  a  Pravaz'  syringe  into  one  of  the 
lymph  spaces  of  such  a  frog,  no  serious  disturbance  of  the  health 
of  the  animal  is  caused.  The  stuffed  lymphoid  cells  now  pene- 
trate as  pus-corpuscles  from  the  periphery  into  the  cornea,  to 
adhere  to  the  place  of  irritation.  It  is  only  a  few  of  these  cells, 
however,  which  bear  the  colored  granules  in  their  bodies  as  a 
mark  of  their  origin.  A  considerably  larger  number  of  these 
can  only  be  obtained  when  this  coloring  matter  has  been  in- 
jected for  several  consecutive  days  into  the  various  lymphatic 
spaces. 

Either  the  fresh  organ,  incised  several  times  at  its  margins,  or 
the  organ  impregnated  with  gold,  may  serve  for  examination. 

However,  even  in  a  cauterized  cornea,  if  it  is  only  obtained 
living,  lymphoid  cells  accumulate  in  such  quantities  around  the 
point  of  irritation,  that  the  migratory  cells  present  in  it  at  the 
moment  of  separation  do  not  suffice  to  supply  the  demand 
(Hoffmann  and  Recklinghausen).  An  origin  of  these  cellular 
elements  from  the  stellate  corneal  corpuscles  cannot,  according 
to  this,  be  denied. 

The  network  of  blood-vessels  which  may  cover  the  anterior 
surface  of  the  cornea,  as  a  result  of  inflammation,  requires,  after 
the  beautiful  statements  made  by  Thiersch  concerning  the  vas- 
cularization  of  wounds  (p.  392),  a  renewed  investigation. 

Portions  which  have  been  removed  are  regenerated  by  newly 
formed  corneal  tissue.  The  yellowish  margin  which  the  cornea 
shows  in  the  so-called  arcns  senilis,  consists  of  a  deposition  of 
fat  in  the  corneal  cells,  and  also  in  their  interstitial  substance ; 


OKGANS    OF    SENSE.  589 

it  is  therefore  one  of  those  commencing  fatty  degenerations, 
such  as  likewise  make  their  appearance  at  a  more  advanced  age 
in  other  parts  of  the  body. 

Cornea!  preparations  may  be  tinged,  and,  after  extraction  of 
their  water  by  means  of  absolute  alcohol,  mounted  in  Canada 
balsam.  A  moist  mounting  in  watery  glycerine  is,  as  a  rule, 
employed. 

The  tissue  of  the  sclerotica,  as  is  known,  is  continuous  with 
that  of  the  cornea,  but  consists,  after  the  manner  of  the  fibrous 
membranes,  of  a  fibrillated  intercellular  substance,  which  is 
changed  by  boiling  into  ordinary  gelatine,  and  not,  like  the  cor- 
nea, into  choiidrin.  The  flattened  bundles  of  these  fibril Ise 
cross  each  other  nearly  at  right  angles.  Fine  elastic  elements 
and  a  reticulum  of  connective-tissue  corpuscles  stand  out  from 
the  hyaline  interstitial  substance  after  the  application  of  acetic 
acid. 

The  fresh  tissue  teased  out  into  fine  pieces,  and  objects  hard- 
ened or  dried  in  the  same  manner  as  the  cornea,  serve  for  the 
examination.  If  the  iris  and  choroid  have  been  retained  on 
them,  the  immediate  transition  of  these  tissues  into  that  of  the 
sclerotic  may  be  finely  observed ;  likewise  the  transverse  section 
of  the  canal  of  Schlemm,  the  origin  of  the  musculus  ciliaris 
and  the  prolongation  of  the  membrane  of  Descemet  into  the 
so-called  ligamentum  iridis  pectinatum. 

The  system  of  the  uvea  consists  of  the  choroid  and  iris,  mem- 
branes which  contain  muscular  fibres  and  are  rich  in  pigment 
and  vessels.  They  are  covered  on  their 
inner  surfaces  by  a  pigmented  pavement 
epithelium  (fig.  326),  the  so-called  poly- 
hedral pigment-cells  of  an  earlier  epoch. 
For  the  demonstration  of  these  cells 
(which  are,  however,  with  much  greater  Fig.  326.  pigmented  paye- 

7  ment    epithelium    (so-called 

propriety  to  be  included  with  the  retina),  {^ys^eederal  ^s11161^  ceUs->  of 
the  fresh  eye  may  be  used,  or  one  which 
has  been  divided  and  hardened  either  by  means  of  chromic 
acid,  chromate  of  potash,  or  Muller's  fluid.  Small  portions  of 
the  black  covering  of  the  exposed  inner  surface  may  be  re- 
moved with  the  scalpel  or  the  cataract-needle.  They  are  then 


590  SECTION   TWENTY-SECOND. 

to  be  spread  out  with  needles  or  the  brush,  and  covered  with  a 
right  thin  covering  glass.  Strongly  hardened  eyes  permit  of 
transverse  sections  of  the  entire  uvea,  and  hence  profile  views 
of  the  epithelial  covering. 

To  convince  yourself  that  we  have  here,  in  fact,  a  pavement 
epithelium  which  has  assumed  a  peculiar  heterogeneous  appear- 
ance from  the  excessive  pigmentation,  take  an  Albino  eye,  that 
of  a  white  rabbit,  or  the  unpigmented  covering  on  the  so-called 
tapetum  of  one  of  our  ruminantia.  An  ordinary  mosaic  of 
polyhedral  cells  will  be  perceived,  and,  in  the  latter  locality,  ap- 
pearances will  be  at  the  same  time  obtained  which  show  that 
on  the  peripheral  portion  of  the  tapetum  cells,  with  a  scanty 
deposition  of  melanine,  form  the  transition  into  ordinary  pig- 
ment-cells. 

The  choroid  proper  consists,  as  is  known,  of  a  soft  connective 
tissue,  showing  stellate  cells  united  in  a  reticular  manner,  and 
which  is  permeated  by  an  extraordinary 
quantity  of  blood-vessels.  These  cells 
characterize  themselves  by  a  great  dis- 
position to  develop  pigment  molecules  in 
their  bodies  and  to  thus  become  stellate 
pigment-cells  (fig.  327). 

.We  distinguish  several  layers  of  the 
choroid.  An  external  looser  stratum  of 
soft  connective  tissue,  rich  in  pigmented 
stellate  pigment-  cells  Gamina  f  usca>  >  supra-choroidea), 
Cfr?mCtthe  serves  f°r  the  connection  with  the  inner 
surface  of  the  sclerotic.  Its  structure 
maybe  readily  recognized  in  fresh-picked  preparations ;  likewise 
its  relations  with  the  neighboring  tissues  in  sections  through  the 
sclerotic  and  uvea  of  an  eye  strongly  hardened  in  chromic 
acid. 

Beneath  the  lamina  f usca  follows  a  middle  layer  of  this  con- 
nective-tissue substance,  presenting  the  larger  arterial  and 
venous  ramifications.  The  fresh  tissue,  or  an  eye  which  has 
been  injected  with  a  transparent  mixture,  serves  for  the  recog- 
nition of  this  slightly  pigmented  layer.  Finally,  as  a  third 
layer  appears,  a  more  homogeneous  unpigmented  stratum,  the 


OEGANS    OF    SENSE. 


591 


Fig.  328.  Capillary 
arrangement  from  the 
chono-capillaris  of  the 
cat. 


so-called  chorio-capillaris,   which  contains  a  remarkably  rich, 
very  narrow-meshed  reticulum  of  delicate  capillary  vessels  (fig. 
328).      Here  also    recourse  may  be  had  either  to  an  injected 
organ  (calf,  sheep,  cat),  or  a  portion  of  choroid 
may  be  taken  from  a  chromic  acid  prepara- 
tion and  freed  as  well  as  possible  from  the 
external  layers,  and,  by  cautious  brushing  in 
glycerine,    from    the     pigmented    pavement 
epithelium  which   covers   the   inner  surface. 
A  sufficient  quantity  of  blood-corpuscles  will 
generally  be  found  retained  in  the  capillary 
network. 

The  fine  hyaline,  more  independent  boun- 
dary layer  of  the  chorio-capillaris,  towards 
the  pavement  epithelium,  has  been  designated 
as  the  elastic  layer  of  the  choroid.  For  its  primary  recognition 
a  fold  of  the  fresh  choroid  may  be  used;  acids  and  alkalies 
serve  as  media. 

These  lamellae  undergo  interesting  senile  metamorphoses, 
thickenings,  spherical  and  druse-like  concretions,  frequently 
with  deposits  of  lime-molecules,  which  may  dislodge  the  pig- 
ment epithelium  and  compress  the  retina  (Miiller).  Other 
hyaline  membranes  of  the  eye  also  increase  in  thickness  with 
age. 

The  injection  preparations  mentioned,  deprived  of  their 
water  with  alcohol,  may  be  beautifully  mounted  in  cold  Canada 
balsam  (diluted  with  chloroform) ;  the  others  are  to  be  mounted 
moist. 

For  the  primary  recognition  of  the  ciliary  muscle,  sections 
from  a  dried  eye  may  be  used.  Here  the  rows  of  fibres 
running  in  a  meridional  direction  may  be  perceived,  and  on 
good  sections  also  the  circularly  arranged  ones  which  Miiller 
discovered.  For  further  investigations,  use  the  reagents  cus- 
tomary for  the  connective  tissue  and  the  contractile  fibre-cells, 
the  30-40  per  cent,  potash  solution,  the  chloride  of  palladium 
with  a  subsequent  carmine  tingeing,  the  double  staining  of 
Schwarz,  etc.  According  to  Flemming  the  contractile  fibre- 
cells  may  still  be  isolated,  after  hardening  in  chloride  of 


592  SECTION    TWENTY-SECOND. 

palladium,  by  means  of  the  potash  solution  mentioned.  A  long, 
24  hours'  action  of  the  latter  is  then  necessary. 

The  examination  of  the  ciliary  body  is  to  be  made  on  fine 
sections  from  an  eye  which  has  been  injected  with  transparent 
gelatine  fluids,  and  hardened  in  chromic  acid  or  alcohol.  The 
delicate  rich  reticulum  of  vessels  may  in  this  way  be  most 
accurately  followed.  Here,  as  with  the  iris,  the  eye  of  the  white 
rabbit  injected  with  carmine  deserves  the  preference. 

For  the  primary  recognition  of  the  structure  of  the  iris,  avoid 
dark-eyed  creatures,  as  the  stellate  pigment -cells  which  occur 
in  their  tissue  increase  the  difficulty  of  the  examination  very 
much.  The  eye  of  a  new-born  or  of  a  bright-eyed  child  deserves 
to  be  recommended  here.  The  methods  consist,  after  the 
removal  of  any  pigmented  epithelial  layer  wrhich  may  be 
present  (and  which  may  be  previously  macerated  in  acetic  or 
oxalic  acid)  by  means  of  the  brush,  firstly  in  tearing,  then  in 
the  examination  of  whole  pieces  with  the  use  of  acetic  acid 
for  connective  tissue,  and  of  the  dilute  soda  solution  for  the 
nerves.  For  the  smooth  muscular  tissue  use  the  reagents  now 
generally  employed  for  that  tissue,  and  which  have  just  been 
mentioned.  One  may  thus  convince  one's  self  of  the  existence 
of  a  dilatator  pupillae,  concerning  which  numerous  controversies 
have  lately  arisen,  and  which  is,  nevertheless,  not  so  very 
difficult  to  recognize.  The  whole  or  half  of  the  iris  of  a  small 
white  rabbit  may  be  used  for  the  study  of  the  coarser  arrange- 
ment of  the  muscles  when  treated  with  acetic  acid,  and  also 
with  the  addition  of  soda  for  following  the  nerves  of  the  iris 
with  lower  magnifying  powers.  Such  objects,  tinged  with 
carmine  and  washed  out  in  weak  acetic  acid,  become  very 
handsome,  as  do  also  transparent  injections  of  the  blood-vessels. 

There  is  nothing  especial  to  be  remarked  concerning  the 
methods  of  preservation. 

Concerning  the  refracting  organs,  the  lens  and  the  vitreous 
body,  the  tissue  of  the  latter  has  already  been  mentioned  in 
one  of  the  preceding  sections  of  our  book  (p.  269) ;  the  crys- 
talline lens,  on  the  contrary,  although  in  reality  an  epithelial 
structure,  has  not  yet  been  discussed. 

The  fresh  eye   of   any  somewhat  large  mammalia!  animal 


ORGANS    OF    SENSE. 


593 


may  be  employed  for  the  examination  of  the  lens-capsule 
(fig.  329  a)  and  of  the  extremely  delicate  pavement  epithe- 
lium (b)  which  occurs  on  the  posterior  surface  of  the  anterior 
segment  of  the  capsule.  The  capsule,  isolated  with  the  lens,  is 
to  be  liberated  by  an  incision  and  placed  in  fragments  under 
the  microscope,  with  the  addition  of  vitreous  fluid.  Weak 
powers,  with  a  strongly  shaded  field,  show  the  borders  and 
folds  of  the  hyaline  membrane  at  once.  Stronger  objectives 
show  the  thoroughly  homogeneous  structure  of  the  hyaline  mem- 
brane, and  with  repeated  considerable  shading,  the  pavement- 
shaped  epithelium  may  be  recognized.  The  addition  of  aniline 
red  is  here  very  convenient,  as  the  tingeing  follows  very  rapidly 


Fig.  320.  Diaerammatic  represen- 
tation of  the  human  crystalline  lens. 
a,  the  capsule ;  c,  the  lens-fibres  with 
widened  ends,  (rf)  becoming  inserted 
at  t  he  anterior  layer  of  the  epithelium 
(6),  and  also  inserted  posteriorly  into 
the  capsule  (e);  f,  the  so-called 
nuclear  zone. 


Fig.  c£0.  Lens-fibres  of  the  human 
embryo  of  eight  months,  r/,  Fibres  with 
a  nucleus ;  6,  one  which  still  presents  the 
cellular  character ;  c,  the  flattened  form 
of  the  side  view ;  d,  fibres  with  two  and 
three  nuclei. 


and  without  any  alteration  of  the  tissue. 

also  accomplish  the  object. 
38 


Other  tingeing  methods 


594  SECTION    TWENTY-SECOND. 

On  a  fresh  section  of  a  lens,  however,  even  with  the  use  of 
these  two  accessories,  one  would  be  able  to  recognize  the  lens- 
fibres  (fig.  330)  only  very  incompletely. 

Various  accessories  are  to  be  recommended  here,  as  the 
maceration  in  highly  diluted  sulphuric  acid  (4—5  drops  of  the 
acid  of  1.839  sp.  wt.  to  one  ounce  of  water),  which  isolates  the 
lens-fibres  (v.  Becker);  in  muriatic  acid  of  0.1-1  per  cent. 
(Moriggia)  ;  further,  the  preparatory  hardening  in  chromic  acid, 
bichromate  of  potash,  or  Miiller's  fluid  (Zernoif).  The  object 
may  likewise  be  obtained  with  alcohol,  though  not  so  well  ; 
and  also  by  peeling  off  thin  scale-like  portions  from  a  dried  lens. 
The  organ  being  of  itself  quite  transparent,  with  many  chromic- 
acid  preparations,  the  use  of  media  which  tend  to  increase  the 
transparency,  such  as  glycerine,  is  to  be  avoided.  Such  objects 
may  occasionally  be  very  suitably  tinged  with  aniline.  Others, 
which  are  more  opaque,  can  be  again  rendered  transparent  by 
means  of  glycerine  or  acetic  acid.  An  immersion,  lasting  for 
15  minutes,  in  a  nitrate  of  silver  solution  of  0.125-0.1  per  cent. 
has  also  been  praised  (Robin  sky). 

The  lens-tubes  and  the  nuclei  of  the  equatorial  zone  readily 
appear  (fig.  329  f).  To  recognize  the  relations  of  origin  of  these 
fibres  to  the  epithelium  of  the  capsule,  one  may  use  a  strongly 
hardened  lens  which  is  within  its  capsule,  and  the  equatorial  as 
well  as  meridional  sections  from  that  region. 

Equatorial  sections  may  be  obtained  from  the  adequately 
hardened  crystalline  lens,  and  may  thus  permit  of  the  recogni- 
tion of  the  delicate  mosaic  of  the  lens-tubes  cut  at  right  angles. 
A  lens  which  has  become  considerably  dried  in  the  air,  if  em- 
ployed at  the  proper  moment,  has  not  unfre- 
quently  acquired  such  a  degree  of  consistence 
as  to  permit  of  convenient  cutting  without 
rig.  88i.  Trans-  splintering.  From  it  very  handsome  transverse 
the  sections  may  be  obtained  (fig.  331).  A  similar 


appearance  may  be  obtained  from  ground  sec- 
tions of  a  strongly  hardened  lens.  The  previous  saturation 
with  a  mixture  of  gum  mucilage  and  a  little  glycerine  is  also 
to  be  tried  in  drying. 

Opacities  of  the  lens  capsules,  in  part  with  depositions  of  ele- 


OEGANS    OF    SEKSE. 


595 


mentary  granules,  likewise  embedments  of  fat-molecules  in  the 
epithelial  cells  and  lens-fibres,  of  granules  between  the  latter, 
deposits  of  lime,  etc.,  are  not  unfrequent  occurrences.  The 
methods  of  examination  are  the 
same. 

Human  and  mammalial  embry- 
os, hardened  in  absolute  alcohol 
or  chromic  acid,  serve  for  ascer- 
taining the  primary  origin  and 
the  foetal  structural  conditions  of 
the  lens  (fig.  332)  and  the  vitreous 
body.  In  embryos  of  the  sheep 
of  6-7'",  everything  is  still  cellu- 
lar; in  human  foetuses  of  about 
8-9  weeks,  the  lens  also  seems  to 
be  constituted  of  only  delicate 
spindle-shaped  cells  (Kolliker). 
The  condition  of  a  pig's  foetus 
of  two  inches  is  shown  in  our 
figure.  Foetuses  of  this  animal  of 
nucleus  (Schwann). 

Preservation  is  to  be  attempted  with  strongly  watered  glyce- 
rine. 

The  membrana  hyaloidea  is  readily  recognized  in  the  hard- 
ened, and  also  in  the  fresh  organ. 

In  the  latter  condition,  after  brushing  off  the  epithelium,  the 
fibres  of  the  zonula  Ziimii  may  be  perceived  with  some  difficul- 
ty, but  they  appear  far  more  beautifully  and  sharper  in  the 
hardened  eye. 

If  we  now  proceed  to  the  nervous  portion  of  the  eyeball,  the 
retina,  there  lies  before  us  in  the  so  difficult  to  comprehend, 
extremely  complicated  structure  of  the  most  delicate  and 
changeable  membrane,  one  of  the  most  troublesome,  but  like- 
wise also  most  attractive  objects  of  microscopic  investigation. 
An  infinite  amount  of  work  has  already  been  done  in  older  and 
more  recent  times  in  the  investigation  of  the  so  wonderful  reti- 
na ;  and,  though  the  knowledge  concerning  this  membrane  has 
made  very  great  progress  by  the  aid  of  the  modern  accessories, 


Fig.  332.  a— c,  Lens-cells  of  a  two-inch 
foetus  of  the  pig.  a,  Original  cells  ;  6, 
oval  elongated  :  c,  grown  longer  in  the 
transition  into  lens-tubes ;  d,  epitheli- 
um of  the  lens,  from  an  eight  months1 
human  embryo ;  e,  cells  of  the  so-called 
humor  Morgagnii. 


"  have  already  a  fibrous 


596  SECTION    TWENTY-SECOND. 

there  remain  to  the  present  hour  unsolved  many  textural  ques- 
tions of  physiological  importance. 

To  obtain  the  primary  review  preparations  recourse  will  now- 
adays be  generally  had  to  an  artificially  hardened  eye.  An 
opened  eyeball  may  be  immersed  in  chromic  acid  of  0.5-0.2 
per  cent,  (if  unopened  the  concentration  may  be  increased),  or 
the  corresponding  quantity  of  the  bichromate  of  potash.  At  pres- 
ent we  can  recommend  nothing  more  highly  for  the  unopened 
bulb  than  Miiller's  fluid.  It  preserves  the  cones  and  rods  very 
beautifully,  which,  with  the  other  solutions,  does  not  succeed  or 
only  very  incompletely ;  the  examination  may  be  made  after 
2-3  weeks  (but  also  much  later).  Alcohol,  which  was  formerly 
regarded  as  inappropriate,  has  more  recently  been  highly  recom- 
mended (Ilenle,  Hitter) ;  likewise,  for  the  connective-tissue  part 
at  least,  the  mixture  (mentioned  at  p.  140)  of  chloride  of  plati- 
num and  chromic  acid  (Merkel). 

*  Thin  vertical  sections  from  the  f undus  of  the  bulb  may  also 
be  readily  made  with  a  sharp  knife  with  such  retinas. 

Such  a  vertical  section,  examined  in  the  hardening  fluid  with 
the  addition  of  a  little  glycerine  (according  to  circumstances  it 
may  very  suitably  be  previously  tinged  with  glycerine-carmine), 
and  cautiously  covered  with  a  very  thin  covering  glass,  shows  at 
once  the  numerous  layers  of  the  retina  which  were  conquered 
for  science  with  such  difficulty,  and  of  which  the  adjacent  sketch, 
(fig.  333)  may  recall  the  necessary  conception  to  mind.  The 
various  localities  of  the  retina,  if  treated  in  the  same  manner, 
will  present  their  primary  structural  peculiarities. 

Assisted  by  the  advanced  knowledge  of  the  connective  sub- 
stances, one  may  at  present  recognize  in  any  retina  a  consider- 
ably developed  connective-tissue  framework  substance,  the  per- 
ception of  which  is,  however,  considerably  impeded  by  the  ex- 
traordinary fineness  of  the  elements.  The  best  investigation  of 
this  framework  substance  was  made  by  M.  Schultze. 

This  is  permeated  by  the  nervous  elements,  among  which 
are  to  be  enumerated  the  layer  of  optic  nerve-fibres  (fig  333,  7), 
and  of  the  ganglion-cells  of  the  inner  portion  (6) ;  then  the 
cones  (and  rods)  of  the  outer  layer  (1),  and  likewise  a  part  of  the 
elements  of  the  granular  layers  (2, 4) ;  as  also,  finally,  a  system  of 


ORGANS    OF    SENSE. 


597 


radially  arranged  finest  nerve-fibres,  which  have  only  recently 
been  distinguished  from  the  connective-tissue  supporting 
fibres. 

The  verification  on  the  fresh  eye 
will  be  necessary  even  for  what  has 
thus  far  been  described.  The  eye 
is  to  be  opened  under  iodine-serum 
in  a  dish,  and  a  portion  of  the  retina 
removed.  A  fold  having  been  care- 
fully made,  and  a  piece  of  thin  glass 
placed  near  it,  to  protect  it  from  the 
pressure  of  the  covering  glass,  the 
various  layers  may  be  more  or  less 
distinctly  recognized.  Fine  verti- 
cal sections  are,  nevertheless,  more 
suitable.  Do  not  believe  that  im- 
mense skill  is  necessary  for  their 
preparation.  The  piece  of  retina 
carefully  separated  from  a  fresh  ox- 
eye  is  to  be  placed  on  the  micro- 
scopic glass  slide,  or  on  a  cork  plate, 
and  a  little  vitreous  fluid  or  iodine- 
serum  added.  The  "attempt  is  then 
to  be  made  with  a  sharp  moistened 
blade,  such  as  that  of  a  cataract- 
knife,  or  the  convex  one  of  a  small 
scalpel,  by  careful  pressure  and  a 
rocking  motion,  to  obtain  as  fine  as  possible  sections.  Many  of 
these  attempts  will  fail,  but  a  few  objects  will  possess  sufficient 
thinness  to  permit  of  a  successful  examination,  if  treated  with 
the  same  precautions  as  a  fold. 

For  further  studies  such  sections  (in  which  it  is  true  one  is 
not  protected  from  a  displacement  of  the  elements,  and  which 
therefore  require  a  comparison  with  other  methods)  may  be 
further  picked.  It  is  also  suitable  to  employ  with  them  a 
weak  chromic  acid  or  the  dilute  Miiller's  fluid. 

A  portion  of  the  above-mentioned  connective-tissue  frame- 
work of  the  retina  may  be  recognized  even  by  the  aid  of  the 


Fig.  333.  Vertical  transverse  sec- 
tion of  the  human  retina  (made  about 
half  an  inch  from  the  point  of  entrance 
of  the  optic  nerve).  1.  Layer  of  rods 
and  cones ;  2,  external  granular  layer; 
3,  inter-granular  layer ;  4,  internal 
granular  layer ;  5,  fine  granular  layer ; 
6,  layer  of  ganglion-cells ;  7,  expansion 
of  the  optic  nerve-fibres;  8,  radial 
fibres;  9,  their  insertion  into  the  inner 
limiting  membrane,  the  membrana 
limitans  interna,  10. 


598  SECTION    TWENTY-SECOND. 

previous  methods;  though  even  a  half-way  sufficient  view  is 
never  obtained.  As  Schultze  has  shown,  other  methods  are 
necessary  for  this  purpose,  the  same  as  have  already  been  men- 
tioned at  the  organs  of  smell. 

Among  these  are  to  be  enumerated  chromic  acid  in  a  con- 
dition of  extreme  dilution  (p.  131),  the  very  watery  sulphuric 
acid  (p.  127),  and  the  concentrated  oxalic  acid  solution  (p.  133). 
To  obtain  a  primary  view  of  the  connective-tissue  framework 
structure  of  the  retina,  that  investigator  says  that  the  eye  of  a 
fish  is  to  be  used,  as  the  arrangement  is  easier  to  understand 
here  than  in  the  mammalial  animal.  The  bulb  of  a  river  perch 
which  has  just  been  killed  is  to  be  divided  through  the  equator 
and  placed  for  three  days  in  the  familiar  highly  diluted  chromic 
acid  solution, which  contains  J,  -J-,  -J-  grain  of  the  acid  (or  £-2  grs. 
of  bichromate  of  potash)  to  the  ounce  of  water.  The  exami- 
nation is  then  to  be  made,  cautiously  picking,  and  using  the 
high  magnifying  powers  of  a  Hartnack's  immersion  system. 
While  the  connective-tissue  framework  substance  is  thus  ren- 
dered recognizable  by  the  chromic-acid  solution,  the  latter  has 
likewise  the  already  mentioned  excellent  property  of  causing 
varicosities  on  the  finer  nerve-fibres,  and  of  rendering  it  possi- 
ble to  distinguish  the  two  systems  of  fibres  in  the  retina  as  in 
the  regio  olfactoria. 

The  concentrated  watery  solution  of  oxalic  acid  is  also  an 
excellent  medium  for  this  examination  and  discrimination,  as  it 
renders  the  connective-tissue  framework  paler  and  hardens  the 
nervous  elements  somewhat,  and  thus  renders  them  more  dis- 
tinct. One  is  not  confined  to  a  definite  time  by  this  means,  as 
the  examination  may  be  made  after  a  few  hours,  or  even  after 
several  days. 

Sulphuric  acid  of  0.6  per  cent,  preserves  the  nervous  elements 
yery  well,  but  also  at  the  same  time  those  of  the  connective- 
tissue  framework. 

The  scientist  mentioned  afterwards  found  in  osmic  acid  an 
important  accessory  for  the  investigation  of  the  textural  condi- 
tions under  consideration.  "We  shall  return  to  the  same. 

By  such  methods  the  connective-tissue  framework  substance 
has  presented  the  following  arrangement  (fig.  334,  A). 


OEGANS    OF    SENSE. 


599 


The  entire  retina  is  permeated  by  it,  with  the  exception  of 
the  bacillar  layer.     A  system  of  radial  or  Miillerian  supporting 


Fig  334,  Eiagrammatic  representation  of  the  retina  of  man  and  the  vertebrata,  after  M. 
Schultze.  A,  connective-tissue  framework  of  the  retina,  or,  membrana  limitans  externa ;  e, 
radial  or  Miilleiian  supporting  fibree^with  their  nuclei  e' ;  I,  limitans  mtema ;  d,  framework 
substance  of  the  inter-granular,  and  g  of  the  fine  granular  layer.  B,  nervous  elements  of  the  retina. 
6,  rods  with  outer  and  inner  portions,  as  well  as  the  rod-granule  (&')  ;  c,  cone  with  the  rod  and 
granule  (c ')  ;  d,  expansion  and  apparent  termination  of  the  cone-fibres  in  the  inter  granular  layer, 
with  the  transition  into  finest  fibrillae  ;  /,  granules  of  the  inner-granular  layer ;  g,  confused  mass 
of  finest  fibrillae  in  the  fine  granular  layer;  A,  ganglion-celle ;  A',  their  axis-cylinder  processes; 
<,  layer  of  nerve-fibres. 

fibres  (e)  forms,  with  its  innumerable  fine  processes,  a  delicate 
network  which,  in  two  places,  namely,  in  the  inter-granular 
layer  (d)  as  well  as  the  fine  granular  layer  (^),  assumes  an 


600  SECTION   TWENTY-SECOND. 

extraordinary  fineness  and  compactness,  and  here  becomes 
changed  to  a  regular  spongy  tissue,  related  to  that  of  the  gray 
substance  of  the  brain.  Inwards,  these  supporting  fibres, 
uniting  together  and  spreading  out  in  a  peculiar  manner,  form 
a  hyaline  connective-tissue  boundary  layer,  the  membrana 
limitans  interna  (I).  Externally,  over  the  so-called  external 
granular  layer,  a  second  similar  boundary  layer,  but  finer  and 
perforated  in  a  sieve-like  manner,  may  be  seen.  This  is  the 
limitans  externa  (a). 

If  the  finer  textural  conditions  of  the  nervous  elements  of  the 
retina,  as  well  as  finally  the  connection  of  the  same,  are  to  be 
investigated,  the  methods  which  have  until  recently  been  em- 
ployed in  this  difficult  domain  have  already  been  mentioned  in 
the  preceding. 

Maceration  may  be  accomplished  with  the  various  acids  men- 
tioned for  the  connective-tissue  framework,  among  which  the 
highly  diluted  solutions  of  chromic  acid  have  been  most  em- 
ployed. Corresponding  solutions  of  the  bichromate  of  potash, 
as  well  as  Mtiller's  fluid  diluted  with  water,  are  also  to  be 
recommended  as  suitable.  A  careful  picking  naturally  follows. 
For  hardening,  to  subsequently  obtain  very  fine  sections,  the 
stronger  solutions  of  chromic  acid  and  its  potash  salt,  as  well 
as,  above  all,  the  Mtiller's  fluid,  are  employed.  A  very  conser- 
vative tingeing  with  carmine  will  render  many  things  more  dis- 
tinct, although  its  value  proves  to  be  less  here  than  for  many 
other  organs. 

We  scarcely  need  to  remark  that  for  such  infinitely  delicate 
textural  conditions  the  strongest  objectives  must  be  used. 

The  rods  and  cones  usually  keep  well  in  weak  solutions  of 
chromic  acid  and  chromate  of  potash ;  the  extremely  dilute 
solutions  mentioned  by  Schultze  are  unserviceable.  The  Miil- 
ler's  eye-fluid  preserves  them  well.  Schultze  found  the  rods 
excellently  preserved  in  the  concentrated  oxalic  acid;  the 
above-mentioned  sulphuric  acid  of  0.6  per  cent,  is  also  useful 
for  the  rods.  The  recognition  of  the  latter  with  the  external 
and  internal  portions  is  relatively  easy  in  the  quite  fresh  eye, 
with  the  addition  of  humor  aqueus  and  vitreous  or  iodine-serum, 
whereby  we  meet  at  the  same  time  with  a  quantity  of  frag- 


OEGANS    OF    SENSE. 


601 


ments  and  in  part  strangely  disfigured  specimens.  A  portion  of 
fresh  retina,  with  the  external  surface  turned  upwards  and 
placed  under  the  microscope  without  a  covering  glass,  forms  the 
best  object  for  the  recognition  from  above  of  the  mosaic  of  the 
rods  and  cones. 


"  Fig.  335.  Structure  of 
the  rods  (Schultze).  1. 
Those  of  the  Guinea-pig 
in  a  fresh  condition,  with 
inner  and  outer  portions 
to  the  lefr,  in  connection 
with  a  transversely  stri- 
ated granule.  2.  Those 
of  the  Macacus  cyno- 
molgus,  macerated  in 
iodine-serum,  with  Hit- 
ter's filament. 


"  Fig.  336.  Structure  of  the  rods  (Schultze). 
1.  from  the  chicken  ;  2,  from  the  frog  (in  a 
fresh  condition) ;  3,  from  the  salamander 
(likewise  fresh) ;  4,  from  the  pike  (also 
fresh) ;  5,  the  division  into  plates  of  a  rod 
from  the  frog  treated  with  a:etic  acid ;  a, 
lenticular  body. 


The  external  and  internal  portions  of  the  rods,  the  former 
(fig.  334  B.  J,  fig.  335  and  336)  of  stronger  refractive  power, 
the  latter  delicately  contoured  and  becoming  reddened  in  the 
carmine  solution  (Braun),  are  to  be  discovered  with  tolerable 
facility ;  likewise  the  very  fine  and  perishable  filament  which 
arises  from  the  pointed  end  of  the  inner  member.  Schultze 
succeeded  years  ago,  with  his  familiar  highly  diluted  chromic 
acid  solutions,  in  demonstrating  varicosities  on  these,  and  there- 
by their  nervous  nature  in  contradistinction  to  the  connective- 
tissue  supporting  fibres. 

The  impossibility  of  following  these  finest  rod-fibres  through 
the  entire  thickness  of  the  retina  was  known  even  at  that  time, 
as  their  course  is  maintained  in  a  radial  direction  over  limited 
portions  only. 


602 


SECTION    TWENTY-SECOND. 


The  recognition  of  the  cones  (fig.  334  c,  fig.  327),  as  well  as 
their  rod-shaped  terminal  portions  (cone-rods),  also  succeeds 
with  the  older  methods,  although  the  extraordinary  change- 
ability of  the  cone-rod  renders  the  perception  of  its  true  struc- 
ture very  difficult. 


Fig.  S37.  Cones,  a, 
from  man,  with  a  de- 
composed external  por- 
tion and  fibrillary  ap- 
nearing  inner  portion; 
Z>,  from  the  Macacus 
UynomolcruF,  after  ma- 
ceration in  dilute  nitric 
acid,  with  the  lenticular 
body  (Schultze). 


Fig.  838.  Fibrillated  cover- 
ing of  the  rods  and  cones, 
after  Schultze.  1.  Rods,  2, 
cones  of  man;  a,  outer,  &, 
inner  portion  ;  c,  rod-filament ; 
d,  limitans  externa,  3.  Rods 
of  the  sheep.  The  fibrillse 
project  beyond  the  inner  por- 
tion :  the  outer  portion  is 
wanting. 


The  external  granular  layer,  occurring  under  the  limitans 
externa,  shows  with  tolerable  facility  the  varicose  rod-fibres,  as 
well  as  the  small  spindle-shaped  and  transversely  striated  cell 
(rod-granule)  embedded  in  it,  with  a  nucleus  and  nucleolus. 


OEGANS    OF    SENSE.  603 

One  likewise  perceives,  joined  to  the  inner  extremity  of  the 
cone,  the  analogous  (but  not,  as  in  the  rod-granule,  fig.  335.  1, 
transversely  striated)  structure,  the  cone-granule.  Years  ago 
II.  Muller  correctly  recognized  differences  in  these  rod  and 
cone-granules.  A  difference  could  be  recognized  between  the 
broader  fibres  passing  from  the  cones  and  the  finer  varicose  rod- 
fibrillse,  and  they  seemed  to  terminate  in  a  strange  manner 
with  conical,  widened,  terminal  portions  at  the  margin  of  the 
inter-granular  layer  (Muller,  Ilenle),  so  that,  for  a  time,  even 
Schultze  had  doubts  of  their  nervous  nature.  Against  this, 
however,  the  macula  lutea,  formed  entirely  of  more  slender 
cones,  with  their  obliquely  arranged  cone-fibres,  formed  an  im- 
portant objection. 

The  inner  granular  layer  (fig.  334  Bf)  likewise  shows  with- 
out difficulty  a  small  cell  with  a  nucleus  and  nucleolus,  analo- 
gous to  that  which  appeared  to  us  as  the  rod-granule  in  the 
external  granular  layer  of  the  retina.  From  both  poles  of  a 
number  of  these  so-called  granules  arise  very  fine  radial  fila- 
ments, in  which,  however,  no  connection  with  the  varicose 
fibres  of  the  rods  can  be  recognized.  Years  ago  Mtlller  and 
Schultze  succeeded  in  distinguishing  the  oval  nuclei  of  the 
framework  of  supporting  fibres  (A,  e)  from  these  granules. 

By  the  aid  of  the  older  methods  one  may  recognize  with 
relative  facility,  especially  in  large  mammalial  animals,  the 
layer  of  the  multipolar  ganglion-cells  (JS  h)  and  its  varying 
thickness  in  the  various  portions  of  the  retina.  Neither  does 
the  flattened  extension  of  the  (as  a  rule  non-medullated)  retinal 
fibres  (i)  in  the  inner  layer  of  nervous  elements  present  any 
great  difficulties,  either  as  surface  views  or  their  vertical 
sections.  An  exquisite  object  is  afforded  by  the  retina  of  the 
rabbit  and  the  hare,  where  our  nerve- tubes,  streaming  in  by 
way  of  exception,  as  two  rows  of  medullated  fibres,  may  be 
everywhere  readily  noticed. 

"We  have  here  mentioned  with  the  most  concise  brevity  the 
chief  results  of  earlier  investigations.  The  great  differences 
which  the  retina  presents  in  the  various  groups  of  vertebrate 
animals  also  becomes  more  and  more  apparent  (M tiller).  The 
gigantic  rods  of  the  frog,  the  peculiar  twin-cones  of  the  osseous 


604  SECTION   TWENTY-SECOND. 

fishes,  the  often  delicately  colored  fat-globules  at  the  base  of 
the  cone-rods  in  birds  and  squamigerous  reptiles,  must  capti- 
vate the  interest  of  the  observer.  We  can  at  present  say  that 
rods  and  cones  are  widely  diffused  among  the  vertebrate 
animals,  but  are  by  no  means  everywhere  present.  Most 
mammalial  animals  (ape,  ox,  horse,  dog,  etc.)  have  them  similar 
to  those  of  man.  The  eye  of  the  bat,  the  hedgehog,  the  mole, 
the  mouse,  and  the  Guinea-pig  has,  however,  only  rods  and  no 
cones.  The  latter  structures  are  quite  scanty  and  undeveloped 
in  the  retina  of  the  rabbit  and  the  cat.  Birds  have  an  excess 
of  cones  (only  in  owls  these  elements  recede  entirely  and 
colored  fat-globules  are  wanting).  Only  cones,  and  no  rods, 
appear  in  the  retinas  of  lizards  and  serpents.  Kays  and  sharks, 
in  contradistinction  to  the  osseous  fishes,  are  entirely  without 
cones  (Schultze).  We  cannot  here  enter  further  into  the 
important  physiological  consequences  of  these  remarkable  con- 
ditions. It  suffices  for  us  to  have  made  mention  of  them  for 
practical  purposes,  for  the  selection  of  materials  for  investi- 
gation. 

As  was  mentioned,  a  further  excellent  accessory  for  the 
examination  of  the  retina  has  become  known  through  M. 
Schultze  in  osmic  acid  (p.  162),  and  this  reagent  has  been 
employed  in  superior  investigations  with  the  greatest  success.* 

For  its  application  a  2  or  1  per  cent,  solution  should  be  kept 
on  hand,  so  that  it  may  be  diluted  at  pleasure  in  a  measuring 
glass.  One  may  go  down  to  0.1  per  cent.,  or  even  lower. 
Stronger  solutions  of  1-0.25  per  cent,  cause  rapid  hardening 
(without  inducing  coagulations),  so  that  after  an  immersion  of 
even  half  an  hour  portions  of  the  retina  may  be  divided,  in  the 
direction  of  their  radial  fibres,  into  lamellae,  and  the  nervous 
elements  may  be  recognized,  while  the  connective-tissue  sup- 
porting apparatus  is  rendered  but  slightly  prominent.  Such 
preparations  may  be  left  for  a  day  in  the  solution,  and,  washed 
out  in  water  (which  also  serves  as  a  medium  for  osmium  pre- 


*  Chloride  of  gold  and  chloride  of  gold  and  potassium  deserve   a  more  ac- 
curate trial  for  the  retina. 


ORGANS    OF    SENSE.  605 

parations),  it  may  be  preserved  for  days  for  further  examina- 
tion likewise  in  alcohol  and  acetate  of  potash. 

The  blackening,  which  appears  very  rapidly,  is  more  regular 
at  the  commencement.  Later,  the  nerve-fibres  frequently 
become  colored,  the  fine  granular  and  inter-granular  layers 
more  intensely  than  the  other  portions.  The  outer  portion  of 
the  rod  appears,  as  a  rule,  darker  and  sharply  contrasted  from 
the  inner  portion,  quite  especially  and  very  remarkably  so  in. 
the  frog  and  in  fishes. 

Weaker  degrees  of  concentration  of  the  osmic  acid  of  0.2 
per  cent,  and  less,  no  longer  cause  hardening  alone,  but  also  ex- 
ert at  the  same  time  a  macerating  effect.  The  preparation  is 
now  less  brittle,  and  permits  of  picking  with  needles.  It  is  gen- 
erally sufficient  to  allow  the  action  to  continue  for  a  half  or  a 
whole  day.  The  nerve-fibres  may  assume  varicosities  in  these 
wratery  solutions. 

The  connective-tissue  framework  becomes  hardened  later 
than  the  nervous  elements. 

To  thoroughly  preserve  the  rods  and  cones,  take  a  vitally 
warm  eye,  remove  the  posterior  segment  of  the  sclerotic  to  be- 
yond the  equator,  and  immerse  in  a  solution  which  contains 
about  two  per  cent,  of  the  dry  acid.  The  desired  effect  is  ob- 
tained in  a  few  hours.  The  fiuid  media  and  preservative  fluids 
have  already  been  mentioned. 

Schultze  arrived  at  important  results  for  the  external  portion 
of  the  retina.  The  rod-fibres  arrive,  as  far  as  the  inter-granular 
layer  (fig.  334  I>),  to  here,  with  slight  intumescences,  withdraw 
from  observation.  The  broader  cone-fibres  are  quite  similar  to 
an  axis-cylinder,  permit  of  the  recognition  of  delicate  longitu- 
dinal striations  (perhaps  as  an  indication  of  a  further  composi- 
tion), and  form  at  the  same  locality  the  already  mentioned 
conical  expansion  (d).  From  the  base  of  the  latter  arises  a  new 
system  of  extremely  fine  fibrillse,  which,  with  numerous  divari- 
cations, assume  another,  and,  indeed,  horizontal  course.  Vari- 
cosities speak  for  the  nervous  nature  of  the  latter  fibrillse. 

The  connection  of  the  nervous  elements  in  the  inner  layers 
of  the  retina  still  remains  quite  obscure.  Whether  the  radial 
fibres  of  the  inner  granular  layer  (/'),  which  are  united  to  a 


606  SECTION    TWENTY-SECOND. 

granule,  are  connected  with  the  confused  mass  of  finest  fibrillse 
which  arise  from  the  resolution  of  the  cone-fibres,  we  are  not 
yet  able  to  say. 

The  similar  mass  of  fibres,  perhaps  arising  from  the  radial 
fibres  of  the  inner  granular  layer,  also  passes  through  the  fine 
granular  layer  (g),  to  finally  pass  over  into  the  fine  or  so-called 
protoplosma  processes  of  the  ganglion-cells  (A),  (comp.  p.  348- 
9,  fig.  175).  Should  this  conjecture  of  Schultze's  prove  to  be 
'true  (whereby  a  parallel  with  the  texture  of  the  gray  substance 
of  the  central  organ  results),  and  should  the  system  of  processes 
of  a  cone-fibre  hereby  enter  into  different  ganglion-cells,  com- 
plication of  the  nervous  channels  would  indeed  result  which 
could  not  be  mastered  by  our  present  accessories. 

Probably  an  inwardly  directed  broad  process  of  the  ganglion- 
cells  of  the  retina  corresponds  to  the  so-called  axis-cylinder  pro- 
cess of  the  central  cell,  and  simply  assumes  the  form  of  a 
primitive  fibre  of  the  nervous  layer  (A'). 

It  would  lead  us  far  beyond  the  narrow  limits  of  this  book, 
and  the  requirements  of  our  circle  of  readers,  were  we  to  here 
make  more  complete  mention  of  the  most  recent  acquisitions 
in  this  domain.  Thus,  a  problematical  axis-filament  has  been 
ascribed  to  the  rods  (fig.  335,  2)  which  is  certainly  wanting  in 
the  outer  portion  (Schultze).  At  the  inner  portion  of  the  rod, 
where  it  joins  the  outer  portion,  a  singular  lenticular  body  of 
semispherical  or  piano-parabolic  form  has  been  met  with  (fig. 
336  a)..  Something  of  the  kind  also  appears  to  occur  in  the 
cones  (fig.  337  b).  For  the  (certainly  transitory)  preservation  of 
these  structures  the  solution  of  the  bichromate  of  potash  may 
be  tried. 

Of  interest  is  furthermore  a  disk-like  structure  of  the  rods 
(fig.  336,  5),  which  was  incompletely  seen  many  years  ago,  but 
which  has  been  recently  more  accurately  recognized  and  studied. 
On  the  fresh  rod  it  is  seldom  that  anything  of  it  can  be  seen, 
only  examinations  with  oblique  light  and  a  rotary  stage  show 
us  a  trace  of  the  same,  if  one  of  the  strongest  immersion  systems 
can  be  used.  It  becomes  distinct  only  when  distending  reagents 
are  resorted  to,  as,  for  example,  dilute  serum  to  which  a  little 
acetic  acid  may  be  added,  dilute  nitric  acid,  etc.  Osinic  acid 


ORGANS    OF   SENSE. 


607 


(1-2  per  cent)  also  affords  good  preparations,  and,  with  careful 
picking  in  water,  presents  transverse  sections  of  these  plates. 
The  same  foliaceous  disintegration  also  occurs  on  the  outer  por- 
tions of  the  cone-rods  (fig.  337,  338,  2  a). 

Finally,  M.  Schultze  (we  iiave  thus  far  quoted  from  his  works) 
found  an  infinitely  delicate  longitudinal  fibrillary  structure  cov- 
ering the  rods  and  cones  externally  throughout  their  entire 
length  (fig.  338).  One  may  think  of  the  primitive  fibrillae  of 
the  axis-cylinders  and  ascribe  the  latter  signification  to  the  rod- 
and  cone-fibres. 

The  macula  lutea  and  fovea  centralis  require  no  new  methods. 
Their  structure  must  be  ascertained  from  the  text-books  on 
histology. 

The  usual  hardening  treatment  with  chromic  acid  and  chro- 
mate  of  potash  (and  alcohol)  also  serves  to  show  the  relation  of 
the  blood-vessels  to  the  retinal  layers,  and  their  advancement  to 


Pig.  339.  Vessels  of  the  human  retina,    a.  arterial,  c,  venous  branches ;  &>  the  capillary  network. 

near  the  intergranular  layer ;  while  the  delicate  vascular  net- 
work in  its  extension  (fig.  339)  (for  the  demonstration  of  which 


608  SECTION   TWENTY-SECOND. 

we  recommend  the  injection  of  the  eye  of  the  ox  and  the  sheep) 
requires  surface  views. 

For  the  investigation  of  the  lymphatics  of  the  eyeball,  a  still 
more  uncertain  domain  (concerning  which  Schwalbe  has  re- 
cently made  valuable  contributions),  use  the  puncturing  method ; 
for  the  posterior  half,  in  the  space  between  the  sclerotic  and 
choroid ;  for  the  anterior  portion,  the  anterior  chamber  of  the 
eye.  Either  a  cold-flowing  watery  Prussian  blue  or  a  solution 
of  gelatine  serves  as  an  injection  mass.  The  practised  hand 
will  resort  to  the  syringe ;  the  constant  pressure  may  possibly 
afford  better  results. 

With  regard  to  the  pathological  changes  of  the  retina,  we 
are  at  present  acquainted  with  hypertrophies  of  the  connective- 
tissue  parts,  with  a  corresponding  degeneration  of  the  nervous 
elements,  proliferations  of  the  granular  layers,  amyloid  bodies, 
fatty  degeneration  of  the  nervous  (but  also  of  the  connective- 
tissue)  parts,  embolia  of  the  retinal  vessels,  likewise  pigmenta- 
tions coming  partly  from  the  extravasated  blood,  partly  caused 
by  the  proliferated  choroidal  epithelium  which  has  penetrated 
the  retina,  and  which  latter  hereby  frequently  lies  near  the 
retinal  blood-vessels,  etc.  Tumors  of  the  retina  are,  as  a  rule, 
either  sarcomata  or  glioma  (p.  358),  and  only  very  rarely  carci- 
nomata. 

Preparations  from  more  hardened  retinas  (after  the  use  of 
Miiller's  fluid)  may  be  readily  preserved  in  glycerine  in  the 
form  of  review  specimens ;  for  many  views  we  would  recom- 
mend tingeing  them  with  carmine.  The  finest  textural  relations 
of  the  several  layers  and  their  elements  could  not,  on  the  con- 
trary, from  the  condition  of  the  microscopical  technique,  be 
preserved  for  a  long  time.  Attempts  to  mount  them  in  their 
macerating  fluids  rapidly  came  to  an  end,  as  a  rule,  in  the 
destruction  of  the  preparation.  M.  Schultze  has  recently 
gladdened  us  with  the  important  information  that  osmium 
preparations  may  be  preserved  for  years  in  a  solution  of  the 
acetate  of  potash  (p.  212). 

Foetal  eyes  may  be  studied  on  very  small  embryos  immersed 
fresh  in  chromic  acid.  With  older  foetuses  the  eye  is  to  be 
taken  out  and  further  treated  in  accordance  with  the  directions 


OEGA^S    OF    SEXSE.  609 

given  for  the  adult.  The  eyes  of  new-born  kittens  are  to  be  re- 
commended for  injecting  the  magnificent  vascular  network  of 
the  membraua  capsulo-pupillaris. 

5.  AVith  regard  to  the  organs  of  hearing,  the  external  parts 
of  the  same,  such  as  the  auricle  and  the  external  auditory  canal, 
require  no  special  directions. 

The  certiminous  glands,  with  their  coil-shaped  bodies  and 
short  excretory  ducts,  are  to  be  examined  in  the  same  manner 
as  the  related  sudoriparous  glands. 

The  membrana  tympani  is  to  be  studied  either  in  the  fresh 
condition,  with  the  aid  of  the  knife  and  needles,  and  with  the 
use  of  acetic  acid  as  well  as  the  alkaline  solutions,  or  the  pre- 
viously dried  organ  is  employed  for  fine  sections,  whereby  we 
would  also  urgently  recommend  carmine  tingeing. 

The  walls  of  the  cavity  of  the  tympanum  and  Eustachian  tube, 
with  the  covering  of  ciliated  cells,  the  ossicula  auditus,  with 
their  porous  bone  substance  and  their  transversely  striated  mus- 
cles, are  to  be  examined  by  the  methods  customary  for  the  tis- 
sues in  question. 

The  investigation  of  the  labyrinth  is  far  more  difficult. 
Even  the  opening  by  means  of  saw  and  chisel  must  be  accom- 
plished with  caution ;  and  from  the  delicacy  of  many  structural 
conditions,  only  quite  fresh,  just  previously  killed  animals  are  to 
be  used.  For  the  primary  examination  the  labyrinths  of  larger 
mammalial  animals,  such  as  the  calf  and  ox,  are  to  be  selected. 
If  a  certain  practice  in  such  procedures  has  once  been  acquired, 
the  exposure  also  succeeds  later  with  smaller  creatures — the  dog, 
the  cat,  and  the  rabbit.  The  great  alterability  of  the  elements 
also  renders  it  necessary,  as  with  the  retina,  to  use  fluid  media 
which  are  as  indifferent  as  possible ;  among  these  he  would  re- 
commend blood-  and  iodine-serum,  vitreous  fluid,  and  dilute 
albumen.  Dilute  solutions  of  chromic  acid  may  also  be  suita- 
bly applied  to  the  fresh  tissue. 

The  hardening  and,  in  general,  the  immersion  in  solutions  of 
chromic  acid,  bichromate  of  potash,  and  Miiller's  fluid  also  ap- 
pears to  be  of  the  greatest  importance  here.  The  latter  fluid, 
diluted  with  an  equal  volume  of  wrater,  may  be  very  highly  re- 
commended. 
39 


610 


SECTION    TWENTY-SECOND. 


The   aggregations   of   ear-stones    or  otoliths   (as    the    polar- 
izing   microscope    teaches,   columns    crystallized   in  the   arra- 

gonite  form)  may  be  perceived 
in  the  sacculi  of  the  vestibule 
as  white  spots,  surrounded  by 
an  especial  thin  membrane. 
They  are  generally  small  and, 
according  to  many  statements, 
possess  an  organic  basis.  Their 
appearance  may  be  represented 
by  fig.  340. 

With  regard  to  the  distribu- 
tion of  the  acoustic  nerve  on 
both  sacculi  of  the  vestibule, 
and  on  the  membranous  ampullae  of  the  semicircular  canals,  the 
coarser  arrangement  is  not  difficult  to  recognize.  The  nerve- 
fibres  enter  duplicatures  of  the  walls,  which  are,  especially  in 
the  ampullae,  distinctly  recognized  as  prominences  projecting 

into  their  cavity.  This  projection, 
called  the  septum  nerveum,  contains 
the  termination.  An  earlier  epoch, 
without  having  any  presentiment  of 
the  difficulties  of  such  investiga- 
tions, would  here  convince  itself  of 
the  presence  of  terminal  loops. 

That  conditions  also  occur  here 
which  are  quite  similar  to  those  we 
have  mentioned  in  connection  with 
other  organs  of  sense  ;  that  there  are 
auditory  cells  as  well  as  olfactory 
and  gustatory  cells,  was  first  demon- 
strated by  Reich  and  M.  Schultze  ; 
the  former  by  the  investigation  of 
the  lamprey,  the  latter  by  that  of 
the  ray  and  shark.  Our  fig.  341 
may  bring  such  conditions  of  the 
plagiostomy  before  the  reader,  and 
show  the  characteristic  cells,  c,  with  their  rod-shaped  projection 


Pig.  341.  From  the  crista  acustica  of 
the  ampulla;  of  Raja  clavata.  «,  cylin- 
der cells ;  6,  basal  cells ;  c,  fibre  cells, 
with  the  upper  rod-shaped  processes  </. 
and  lower  fine  fibrillary  ones  e  :  /,  nerve- 
fibres,  becoming  at  g  pale  ramifying 
axis-cylinders. 


OEGANS    OF    SENSE.  611 

d,  and  their  lower  fine  terminal  filament  e.  The  latter  is  un- 
doubtedly the  terminal  nerve-fibrilla,  although  even  here  a  con- 
tinuous connection  could  be  recognized  by  M.  Schnltze  with 
as  little  certainty  as  in  the  olfactory  organ.  Strange  long  hairs 
also  occur  on  the  peculiar  epithelium  of  this  locality. 

Here  also  chromic  acid,  with  those  dilute  solutions  which  we 
have  had  to  mention  so  frequently  for  the  higher  organs  of 
sense,  plays  at  the  present  time  the  role  of  the  most  important 
accessory.  Osmic  acid  and  chloride  of  gold  will  be  tried  by 
some  subsequent  observer. 

According  to  the  few  observations  which  have  at  present  been 
published,  similar  textural  conditions  appear  to  occur  in  the 
vestibulum  of  the  mammalial  animal  (ox).  Although  all  of  our 
knowledge  of  these  subtile  arrangements  is  still  in  embryo,  a 
penetration  of  the  nerve  fibrillse  into  a  peculiar  epithelium  and 
the  existence  of  specific  cells  is  nevertheless  quite  certain. 


Fig.  34:2.  Side  view  of  the  Cortian  organ,  a,  inner  fibre  ;  &,  commencement  of  the  same ;  c, 
joint  portion  ;  </,  transparent  laminal  appendix  (commencement  of  the  lamina  velamentosa)  ;  e. 
outer  fibre  ;  /,  its  joint  portion  ;  g,  end  at  the  membrana  basilaris  o ;  A,  rod-like  process  of  the 
outer  fibre ;  £,  outer  portion  of  the  lamina  velamentosa ;  f,  Cortian  cells  (*',  their  terminal  fila- 
ments to  the  membrana  basilaris) ;  Z,  Deiters1  cells  (ciliated  cells  D) ;  I',  their  processes  ;  ?n,  larger 
epithelial  cells  bounding  the  outer  portion  of  the  Cortian  organ  ;  n,  small-celled  epithelium  of  the 
zona  pectinata. 

Infinitely  more  difficult,  and  leading  into  a  true  chaos  of  the 
most  intricate  structural  conditions,  is  the  termination  of  the 
nervus  cochlearis  in  the  Reissnerian  cochlear  canal,  or  the  so- 
called  scala  media.  Since  Corti  undertook  the  first  successful 
excursion  into  this  domain  full  of  wonders,  our  knowledge  has 
been  enriched  by  each  of  the  subsequent  investigations  by  the 
discovery  of  new  fragments.  Within  a  period  not  long  elapsed, 
Deiters  especially  has  rendered  the  greatest  service  in  connec- 
tion with  the  structure  of  the  cochlea ;  and  Kolliker,  by  the 
discovery  and  closer  investigation  of  the  almost  forgotten  Reiss- 
nerian  cochlear  canal,  has  established  a  new  acceptation  of  the 


612  SECTION    TWENTY-SECOND. 

scala  media.  Among  the  successors,  Hensen  and  Waldeyer  de- 
serve prominent  mention. 

It  would  lead  us  far  beyond  the  limits  of  this  work  were  we 
to  mention  here  the  structural  conditions  which  have  thus  far 
been  investigated,  especially  the  structure  of  the  so-called  Cor- 
tian  organs  (fig.  342).  Notwithstanding  all  previous  efforts,  the 
knowledge  of  the  nerve  terminations  is  not  as  far  advanced  as 
in  the  other  organs  of  sense.  Probably,  however,  the  terminal 
nervous  structures  of  the  nervus  cochlearis  are  present  in  cer- 
tain cells  which  have  recently  been  more.,  clearly  investigated 
by  Deiters  and  Kolliker.  For  more  accurate  information,  we 
would  refer  to  the  monographic  statements  of  Deiters,  Hensen, 
Kolliker,  and  Waldeyer. 

The  exposure  of  the  parts  in  question  may  be  accomplished 
and  learned  on  the  quite  fresh  auditory  apparatus  of  one  of 
our  larger  cattle  (the  ox).  After  some  practice  this  may  also 
be  gradually  achieved  with  smaller  creatures.  Fragments 
which  are  obtained  in  this  manner  from  the  scala  media  are  to 
be  examined  by  means  of  indifferent  media  or  strongly  diluted 
chromic  acid.  The  latter,  or  chromate  of  potash,  also  serves 
for  the  immersion  and  hardening  of  the  opened  cochlea.  For 
many  cellular  conditions  of  the  Cortian  organs,  high  degrees  of 
dilution,  similar  to  those  introduced  into  histology  by  Schultze, 
are  to  be  tried ;  and  certainly  also  osmic  acid,  chloride  of  gold, 
and  chloride  of  gold  and  potassium.  To  obtain  transverse 
sections  of  the  entire  Keissnerian  cochlear  canal,  the  organ, 
previously  hardened  by  means  of  chromic  acid  or  Miiller's 
fluid,  is  to  be  cautiously  decalcified  by  adding  a  few  drops  of 
muriatic  acid  to  these  fluids  and  frequently  changing  the  entire 
mixture.  The  lamina  spiral  is  of  the  larger  animals  may  be 
isolated  and  exposed  to  such  a  procedure.  The  nerve  distri- 
bution in  the  zona  ossea  may  likewise  be  brought  to  view  in 
this  manner.  Several  years  ago  Heusen,  to  obtain  the  mem- 
brane of  Corti  in  its  position,  made  use  of  a  three  months' 
immersion  in  Miiller's  fluid,  and  injected  tolerably  concentrated 
gelatine  through  a  puncture  in  the  tympanum  secundarium, 
which  then  transuded  into  the  cochlear  canal.  The  external 
wall  of  the  cochlea  was  afterwards  broken  open,  and  the  scala 


ORGANS    OF    SENSE.  613 

media  with  the  gelatine  cast  isolated.  Hensen  also  found 
carmine  imbibition  appropriate  here. 

Waldeyer,  the  latest  investigator  in  this  difficult  domain, 
already  recommends,  besides  the  review  of  fresh  objects  in 
humor  aqueus,  the  osmic  acid,  to  which  he ,  ascribes  the  same 
importance  as  for  the  retina  of  the  eye.  Degrees  of  concen- 
tration of  0.1-1  per  cent,  are  to  be  used ;  the  former  for  pick- 
ing, the  latter  for  hardening.  A  solution  of  chloride  of  sodium 
of  0.25-0.5  per  cent,  rendered  him  excellent  service  for  the 
former  preparations.  Chromic  acid  of  0.05  per  cent,  chloride 
of  gold,  according  to  Cohnheim's  directions,  and  a  1  per  cent, 
solution  of  nitrate  of  silver,  are  likewise  useful  for  many  pur- 
poses. 

To  obtain  good  section  preparations,  remove  as  much  bone 
as  possible  from  large  cochleae,  and  make  two  or  three  small 
openings  into  the  capsule.  Smaller  organs,  on  the  contrary, 
are  to  be  left  intact.  The  cochleae  are  then  to  be  placed  for  a 
day  in  a  liberal  quantity  of  a  solution  of  chloride  of  palladium 
(0.001  per  cent.),  or  in  one  of  osmic  acid  of  0.2  per  cent,  if  the 
organs  are  small;  while  more  voluminous  ones  require  an 
increased  concentration  of  0.5-1  per  cent.  Such  objects  are 
then  to  be  exposed  to  the  action  of  absolute  alcohol  for  24 
hours,  and  at  once  placed  in  the  decalcifying  fluid. 

Waldeyer  found  chloride  of  palladium  (0.001  per  cent.)  with 
Y1^  part  muriatic  acid,  or  chromic  acid  of  0.25-1  per  cent,  most 
serviceable  for  the  latter  purpose.  After  the  decalcification, 
the  preparations  are  to  be  washed  out  with  absolute  alcohol ; 
it  may  then  (for  the  subsequent  preparation  of  sections)  be 
embedded  in  a  piece  of  fresh  spinal  cord  or  fresh  liver,  and  the 
whole  then  replaced  in  the  absolute  alcohol.  During  the 
hardening  the  enveloping  piece  of  organ  shrinks  so  firmly 
around  the  cochlea  that  the  latter  remains  immovable  and 
permits  the  desired  sections  to  be  made. 

Before  this  embedding  the  cavity  of  the  cochlea  may  be 
filled  with  gelatine-glycerine  (1:1),  or  (not  so  good)  with  a 
mixture  of  wax  and  oil.  This  filling,  however,  is  not  absolutely 
necessary. 

The  primary  views  of  the  cochlear  canal  may  be  obtained 


614  SECTION   TWENTY-SECOND. 

without  great  difficulty  from  embryos,  treated  in  a  similar 
manner,  by  means  of  suitable  transverse  sections  through  the 
petrous  bone. 

For  cabinet  preparations  the  same  remarks  apply  which  we 
have  made  (p.  608)  concerning  the  retina.  Preparations  of 
the  Cortian  organ,  however,  I  have  preserved  for  years  entirely 
unaltered  in  watery  glycerine.  Hensen  recommends  the  watery 
solution  of  arsenious  acid  for  mounting.  Acetate  of  potash 
should  also  be  tried. 


INDEX. 


ABDOMIXAL,  typhus,  changes  of  lymphatic 
glands  in,  400,  401  ;  of  their  lymphatics,  402; 
of  the  Peyeriaii  follicles,  450  ;  of  faecal  masses 
in,  453 ;  changes  of  the  spleen  in,  485. 

Aberration,  chromatic  of  the  lenses,  10  ;  chro- 
matic of  the  microscope,  56 ;  spherical  of  the 
lenses,  9  :  spherical  of  the  microscope,  56. 

Abscess,  249. 

Accessories  for  modern  microscopes,  21. 

Accommodative  power  of  the  eye,  2. 

Acetate  of  potash,  138,  212. 

Acetic  acid  and  alcohol  mixture,  141,  142. 

Acetic  acid,  concentrated,  133  ;  Moleschott's  di- 
luted, 134;  Kolliker's  very  dilute,  134;  Frey's, 
134;  for  washing  objects  tinged  with  carmine, 
152 ;  with  glycerine,  152. 

Acetic  acid,  index  of  refraction  of,  121. 

Achorion,  Schonleinii,  566. 

Achromatic  double  lenses,  11 ;  lenses,  11. 

Adenoid  tissue,  nee  Reticular  Connective  Sub- 
stance ;  sarcoma  of  the  mammary  glands,  551. 

Adjustment  of  focus,  apparatus  for,  23,  24. 

Aeby  employs  concentrated  muriatic  acid  for  iso- 
lating muscles,  129,  S20 ;  finds  the  capillaries 
to  consist  of  cells,  376,  377. 

Air-bubbles,  removal  of  from  Canada  balsam, 
206,  207 ;  occurrence  of  in  saliva,  425 ;  in  lung 
preparations,  488 ;  in  sputum,  496. 

Alcohol,  action  of,  140 ;  a  constituent  of  other 
mixtures,  141,  142. 

Alcohol  mixtures,  141;  with  acetic  acid  (Clarke's), 
141 ;  Molescbotfs  mixture,  strong,  142 ;  weak, 
142 ;  with  acetic  and  nitric  acids,  142 ;  with 
soda,  142. 

Alkalies,  136;  their  action  on  the  epidermis, 
262 ;  on  the  tissue  of  the  nails,  264 ;  dilute, 
their  action  on  the  ciliary  motion,  259 ;  on  the 
movement  of  the  spermatozoa,  558. 

Alum  with  corrosive  sublimate  and  chloride  of 
sodium,  213. 

Alveolar  cancer,  285. 

Alveolar  epithelium  of  the  lungs,  490. 
Alveoli  of  the  lungs,  489,  490. 
American  Microscopes,  80-86. '' 

Amici  shows  the  influence  of  the  covering  glass, 
18;  microscope  of ,  75 ;  microscopical  improve- 
ments of,  12 ;  on  the  muscular  filaments  of 
the  house  fly,  325. 

Ammonia,  bichromate  of,  139:  for  the  central 
organ  of  the  nervous  system,  by  G-erlach,  352. 
Ammonia  liquor.  137. 
Ammonia,  molybdate  of,  139 ;  for  salivary  glands 

by  Krause,  421. 
Ammonio-phosphate  of  magnesia  crystals  in  the 

faeces,  453 :  in  the  urine,  533. 
Amyloid  bodies,  358;  degeneration,  see  various 

organs:  reactions,  127.  136,  475. 
Amylon,  see  Starch. 

Analyzer.  52 ;  over  the  ocular.  52 ;    in  the   ocu- 
lar, by  Hartnack,  52. 
Andrejevic  on  biliary  capillaries,  464. 
Aneurisms,  388. 


I  Anilin  blue  as  a  tingeing  medium,  157. 
Anilin  red  as  a  tingeing  medium,  155 ;  for  the 

recognition  of  the  axis  cylinder,  334. 
Anis  oil,  index  of  refraction  of,  121. 
Anthracosis  of  the  lungs,  493. 
Aperture,  angle  of,  of  the  lenses,  8;  of  objectives, 
16;   importance  of,  58;  available  portion  of, 
59 ;  of  Hartnack's  systems,  62,  76 ;  of  Spencer's, 
83 ;  of  other  makers,  62. 
Aplanatic  double  lenses,  11 ;  ey.-pieces,  17. 
Apolar  ganglion  cells,  see  Nervous  System. 
Apparatus  for  drawing,  39. 
Apparatus  for  injecting  by  constant  pressure, 
188;  with  a  column  of  fluid,  188;  with  mercu- 
ry, 189. 

Apparatus  for  measuring,  33;     angles  (gonio- 
meter), 38. 
Apparatus    for    micro-photography,    Gerlach's, 

43 :  Moitessier's,  45. 
Appreciation    of    microscopic    images,  98 ;   of 

their  conditions  of  relief,  99. 
Arcus  senilis,  588. 
Argand  lamp,  90. 
Arnold's  studies  on  smooth  muscles,  314  ;  their 

nerves,  365. 
Arsenious  acid  in  watery  solution,  215;  with 

glycerine,  by  Farrant's,  212. 
Arteries,  see  Vessels. 
Arteriolae  recta;  (kidneys),  519. 
Ascarls  lumbricoides  (ova  in  faeces),  455. 
Asphalt  cement,  222 ;  Bourgogne's,  223 ;  making 

a  border  with.  222. 
Asp  on  injection  of  biliary  passages  in  living 

animal,  466,  note. 
Atheronia  of  the  skin,  565. 
Atheromatous  processes,  388. 
Atrophy,  see  the  Organs;  acute  yellow  of  the 

liver,  471. 

Auditory  apparatus,  609;    ceruminous  glands, 
membrana  tympani.  cavity  of  the  tympanum, 
609:  otoliths,  610;  sacculi  of  the  vestibula  of 
fishes,  610;  vestibulurn  of  themammalial  ani- 
mal, (ill ;    cochlea,  611 ;    Hensen's  method  of 
exposing  the  cochlear  canal,  612 ;  Waldeyer's 
method,  613. 
Auditory  cells,  610. 
Auerbach   on  plexus  myentericus,   343 ;    finds 

the  capillaries  to  consist  of  cells,  376. 
Axis  cylinder  of  the  nerve  fibres,  333. 
Axis  fibrillae  of  the  axis  cylinders,  335. 


Baader's  microscopes,  78. 

Bailey  recommends  Hyaloidiscus  as  a  test  object, 

65 ;  Grammatophora  sublilissima,  65,  68. 
Baryta,  sulphate  of.  as  an  injection  mass,  177, 

185 ;  directions  for  preparing,  177. 
Baryta  water.  137. 
Beale,  works  on  the  microscope,  ix.,  x. ;  treatise 

on  micro-photography,  43 ;  B.  &  Clarke  alco- 


616 


INDEX. 


hoi  mixtures.  141 ;  mixture  of  alcohol,  acetic 
and  nitric  acids,  142 ;  alcohol  and  soda,  142  ; 
for  calcified  cartilage,  288 ;  on  carmine  tinge- 
ing,  154;  cold  flowing  injection  mixtures, 
174 ;  with  Prussian  blue,  183 ;  with  carmine, 
185 :  mounting  fluid,  211 ;  directions  for  pre- 
paring glass  cells,  219  :  on  ganglion-cells,  342 ; 
directions  for  hardening  livers,  462. 

Becherzellen.  434. 

Belegzelle,  427. 

B&neehe  on  micro-photography,  43 ;  his  micro- 
scopes, 79. 

Benzine,  144,  274. 

Berre's  injections,  170. 

Bichromate  of  potash.  138,  139. 

Bidder  on  the.  connective-tissue  framework  sub- 
stance of  the  central  organs  of  the  nervous 
system,  357. 

Bil£,  4,  68 ;  coloring  matter  of,  red,  bilirubin, 
469 :  relation  to,  and  difference  from  hcema- 
toidin,  241,  469. 

Biliary  passages,  finest,  464 ;  capillaries,  injection 
of,  464 ;  filled  by  pathological  concretions,  470 ; 
sediments,  469. 

Bilifulvin,  469. 

Biliphaein,  469. 

Bilirubin  of.  Staedeler,  469. 

Billroth  recommends  chloride  of  iron,  139 ;  direc- 
tions for  brushing,  119 ;  recommends  pyrolig- 
neous  acid  for  decalcifying  bones,  306:  describes 
the  reticulum  of  the  spleen  pulp,  481 :  shows 
the  connection  of  the  muscular  filaments  of 
the  tongue  with  connective-tissue  corpuscles, 
419 ;  directions  for  the  examination  of  dis- 
eased brains,  375 ;  for  the  examination  of  the 
kidneys,  511 ;  for  the  typhoid  spleen,  480. 

Binocular  microscopes,  49 ;  of  Nachet,  50  ;  stereo- 
scopic, 51  ;  arrangement  of  Wenham,  Bid- 
dell,  Boss,  Crouch,  51  ;  first  one  constructed 
by  Grunow,  84 ;  of  Tolles,  84. 

Binocular  stereoscopic  eye  piece  of  Hartnack. 
51 ;  of  Tolles,  84. 

Bipolar  ganglion  cells— see  Nervous  System. 

Bizzozero  on  formation  of  colored  blood  corpus- 
'     cles  from    the    lymphoid    cells  of   the  bone 
marrow,  307. 

Bladder,  urinary,  526;  epithelium  of,  526; 
changes  in  catarrh,  527. 

Blood,  229 ;  to  obtain,  229  ;  colored  cells  of,  229 ; 
colorless  cells  of,  230 ;  their  vital  changes  of 
form,  231 ;  locomotion  and  reception  of  gran- 
ules. 231 ;  dilution  of  the  fluid,  230  ;  quantity 
of  both  varieties  of  cells,  231 ;  plasma,  232 ; 
leucaemia  and  melanaemia,  232 ;  in  embryos, 
233;  formation  from  lymphoid  cells  of  the 
frog,  according  to  Recklinghausen,  233 ; 
method  for  this  observation,  234;  of  living 
animals,  242 ;  examination  of  the  circulation, 
242 ;  Schulze's  slide  for  frog  and  salamander 
larva?,  243;  behavior  of  the  blood  cells  of 
the  living  mammalial  animal,  according  to 
Bollett,  244;  examination  of  the  process  of 
inflammation  in  amphibia  by  Cohnheim,  and  in 
mammalial  animals  by  Strieker  and  Sander- 
son, 244  ;  change  of  the  colored  blood-corpus- 
cles by  the  electrical  discharge,  233 ;  by 
heating,  234;  action  of  chemical  reagents, 
234  ;  coagulated  blood,  236 ;  clots,  236  ;  blcod 
stains,  236;  preserving  as  specimens,  236; 
blood  crystals,  237 ;  haemoglobin,  237 ;  hy- 
drochlorate  of  haematine,  239;  haemin,  240; 
haematoidine,  241  ;  blood  in  vomit,  433 ;  in 
sputum,  498  ;  in  urine,  527. 

Blood  lymph  glands  (spleen),  481. 
Blood-vessels.  376 ;  capillaries,  376 ;  composed 
of  cells,  376;  adventitia,  378;  objects  and 
methods  for  examination,  378  ;  value  of  arti- 
ficial injection,  380  ;  natural  injection,  380 ; 
larger  vessels,  380  ;  their  examination,  381 ; 


drying,  382  ;  capillary  network,  383  ;  straight 
and  circular  network,  385 ;  loops,  385 ;  first  ap- 
pearance in  the  embryo,  386  ;  method  of  inves- 
tigation, 387;  pathological  conditions  of  the 
blood-vessels,  388 ;  atheromatous  processes,  388 ; 
aneurisms,  388  ;  changes  of  the  veins,  889 ;  of 
smaller  vessels,  390  ;  calcareous,  fatty  and  pig- 
ment degenerations,  3'JO ;  melanaemia,  391 ;  em- 
boli,  391 ;  importance  of  the  vascular  cells  in 
pathological  changes,  391 ;  pathological  new 
formations  of  vessels,  391 ;  observations  of 
Thiersch  in  healing  wounds,  392. 

Blood-vessels,  injection  of,  169,  187;  of  patho- 
logical objects,  195  ;  with  the  syringe,  192  ; 
with  constant  pressure,  188;  self -injection  of 
living  animal,  187. 

Blue  glass  for  moderating  artificial  light,  90. 

Bastian  recommends  carbolic  acid  and  glycerine 
as  a  conserving  fluid,  212. 

Bones,  292 ;  preparatory  treatment,  292 ;  decal- 
cification,  292;  isolation  of  the  cells  with 
strong  acids,  293  ;  their  recognition  by  means 
of  carmine  tingeing  and  gold  impregnation, 
294 ;  Sharpey's  fibres,  294 ;  preparation  of 
sections,  295 ;  Reinicke's  process,  295 ;  tex- 
ture of  bone,  296;  lamellae,  lacunae,  and 
canaliculi,  296 ;  mounting  the  sections,  296, 
297 ;  injection  of  the  blood-vessels,  298 ; 
Gerlach's  method  of  filling  the  lacunae  and 
canaliculi,  298;  behavior  in  polarized  light, 
298;  development,  300;  absorption  of  the 
cartilage,  300;  points  of  ossification,  301; 
osteoblasts  of  Gegenbaur,  303;  osteogenous 
and  osteoid  tissue,  305 ;  reabsorption  of  the 
bone  substance,  305,  310  ;  growth,  305  ;  de- 
velopment from  a  connective-tissue  basis, 
306 ;  bone  marrow,  307  ;  origin  of  blood  cells 
according  to  Bizzozero  and  Neumann,  307  ; 
rachitis,  307,308;  foetal  bones,  305,  £06; 
new  formation  under  abnormal  conditions, 
308 ;  callus,  309 ;  regeneration  of  last  por- 
tions, 309 ;  hyperostosis,  exostosis,  and  silero- 
sis,  309 ;  osteo-sarcomse,  310  ;  production  of 
bone  in  connective-tissue  parts,  310 ;  osteo- 
porosis, osteomalacia  and  caries,  310  ;  process 
of  decalcification,  310,  311 :  method  of  ex- 
amining pathological  bones,  311. 

Bothriocephalus  latus,  ova  in  fasces,  456. 

Bourgogne's  microscopic  preparations,  205.  227  ; 
Brunswick  black,  223. 

Bowman's  directions  for  making  chrome  yellow, 
173 ;  theory  of  the  muscles,  324 ;  investiga- 
tion of  the  kidney,  506  :  capsule  of  the  gloin- 
erulus  of  the  kidney,  506 ;  glands  of  the  regio 
olfactoria'in  the  higher  animals,  575. 

Brain,  346  ;  membranes  of,  373  ;   sand,  374. 

Bright's  disease  of  the  kidneys,  524. 

Bronchi,  487. 

Bronchial  glands — see  Lymph  Glands. 

Brooke's  revolving  nose-piece,  92. 

Briicke  defines  the  optical  condition  of  the 
muscular  filament,  327 ;  his  soluble  Prussian 
blue,  180. 

Brunner's  gland,  434. 

Brunonian  molecular  motion,  101 :  in  cells,  101 : 
of  small  crystals,  101 :  their  rapidity,  101 ;  in 
salivary  corpuscles,  425. 

Brushing,  method  of  His,  118,  119. 

Budge  (and  Uechtritz)  recommend  chlorate  of 
potash  and  nitric  acid  for  the  axis  cylinder, 
333 ;  on  the  finest  biliary  passages,  464. 

Burette,  145  ;  for  examining  urinary  sediments, 
535. 


C. 

Callus,  309. 

Camera  lucida  of  Chevalier  and  Oberhauser,  40  ; 
obscura,  eye  compared  to  a,  1. 


IKDEX. 


617 


Camphor,  antiseptic  effect  on  microscopic  fluid 
media,  124 :  and  on  injection  masses,  182. 

Canada  balsam,  its  index  of  refraction,  121 ;  for 
mounting  cabinet  preparations,  206  :  varieties 
of.  207 :  dissolved  in  ether  and  chloroform, 
143.  208:  removal  of  the  excess  from  the 
slide,  207  ;  removal  of  air-bubbles,  206,  207 ; 
artificially  hardened  for  mounting  bones,  297. 

Cancer,  284. 

Cancroid — see  Epithelial  Cancer. 

Caoutchouc  cells,  218;  cement,  221. 

Capillaries,  see  Blood-Vessels. 

Carbolic  acid  with  glycerine  as  a  mounting  fluid, 
212. 

Carbonate  of  lead,  176. 

Carcinoma.  284. 

Caries,  310. 

Carmine,  150 ;  solution  in  ammonia,  150,  155, 
181,  185;  injection  fluids,  180,  181,  184:  with 
glycerine,  151 ;  for  self-injection,  187,  188. 

Carmine  tingeing  invented  by  Gerlach,  150  ; 
washing  in  acetic  acid.  152 :  Beale's  method, 
154 ;  Heidenhain's,  155  ;  Thiersch's,  with  ox- 
alic acid,  153  ;  with  borax,  154 ;  acid  carmine 
fluid,  155. 

Cartilage,  28(5 ;  various  forms,  286 :  material  for 
the  examination  of  hyaline  cartilage,  288  ; 
costal  cartilage,  288 ;  'large  primary  and  se- 
condary cells,  288;  decalcified  cartilage,  288  ; 
method,  288-301 ;  examination  of  reticular  car- 
tilage, 288-289:  action  of  cartilage  in  polarized 
light,  289 ;  destruction  of  the  interstitial  sub- 
stance by  chemical  means,  290  ;  pathological 
cartilage  tissue,  290 ;  methods  of  preserving, 
291. 

Cataract  needle,  109. 

Cavity  ot  the  tympanum,  609. 

Cell,  recognized  by  Swann  as  the  'elementary 
form  of  the  body,  vii :  change  of  form  of  the 
living,  102:  method  of  examining  with  the 
moist  chamber  and  the  warm  stage,  102-105  : 
locomotion  of.  102;  of  pus-cells  through  the 
cavities  of  the  cornea,  249,  250. 

Cementing,  220:  fixing  the  cells  with  marine 
glue,  220  :  with  gutta  percha  cement,  220,  221 ; 
with  india  rubber  dissolved  in  chloroform, 
221 ;  placing  the  covering  glass  in  position. 
222:  cementing  with  Brunswick  black,  221- 
223  :  liquid  stove  polish,  223;  gold  size,  223  ; 
Ziegler's  white  cement,  223 :  Stieda's.  224  ; 
black  mask  lac,  224 :  cementing  Canada  bal- 
sam preparations  with  shellac  varnish,  225. 

Cements,  220-224. 

Central  light  for  illumination,  25 ;  for  examin- 
ing test  objects,  71. 

Central  rays,  refraction  of,  9. 

Cercomonas  intestinalis  of  Lambl,  454. 

Ceruminous  glands  of  the  ear,  609. 

Chamber,  moist,  of  Reeklinghausen,  103;  com- 
bined with  the  warm  stage,  104;  gas,  of 
Strieker,  104. 

Chevalier  and  Selligue  produce  achromatic  ob- 
jectives, 12 ;  construct  camera  lucida,  40  ; 
microscopes,  78. 

Chloride  of  calcium,  138;  constituent  of  pre- 
servative fluids,  215. 

Chloride  of  palladium,  140,  165. 

Chloride  of  silver,  Teichmann's,  177. 

Chloride  of  sodium,  138 ;  in  impregnations  with 
silver,  138,  162 :  with  alum  and  sublimate, 
213 ;  a  constituent  of  preservative  fluids,  213, 
214. 

Chloroform,  143  :  for  recognizing  the  axis  cylin- 
der, 333. 

Cholepyrrhin,  469. 

Cholera  vomit,  432 ;  stools,  453. 

Cholesterine,  occurrence  of  in  nerve  tissue,  359  ; 
in  meconium,  453  ;  in  the  bile,  469. 

Chorio  capillaris,  591. 


Choroid,  590. 

Chromatic  aberration.  10. 

Chrome  yellow  precipitated  in  the  blood-vessels 
by  Bowman,  173  ;  Harting's  method,  176  ; 
Hoyer'p,  183  :  Thiersch's  182. 

Chromic  acid,  129. 

Chrzonszczewsky's  self -injection  of  living  ani- 
mals, 187  ;  of  the  liver,  466  ;  of  the  kidney, 
517. 

Cicatricial  tissue,  284. 

Ciliary  body,  592 ;  muscle,  591. 

Ciliary  movement.  257-260. 

Cinnabar  as  an  injection  mass,  175. 

Circulation,  investigation  of.  in  various  animals, 
242-245. 

Cirrhosis  of  the  liver,  477. 

Chyle.  246;  to  preserve,  247;  chyle  fat  in  cy- 
lindrical cells,  434. 

Clarke's  (and  Beale's)  alcohol  mixture,  141 ;  me- 
thod of  examining  the  central  organ  of  the 
nervous  system,  354,  note. 

Cleaning  the  glasses  of  the  microscope,  95,  96. 

Cloves,  oil  of,  recommended  by  Rindfleisch, 
144. 

Coagulation  of  the  blood,  235 ;  of  the  nerve  me- 
dulla, 332. 

Cochlea,  611. 

Cochlea  canal,  611;  nerve,  611. 

Cohnheim  employed  chloride  of  gold,  163,  164  ; 
confirms  Waller's  observations  on  the  passage 
of  lymphoid  cells  through  the  uninjured  walls 
of  vessels,  245 ;  immigration  of  the  latter  cells 
in  the  inflamed  cornea,  586:  examines  sec- 
tions of  frozen  striated  muscle,  318 ;  C.  and 
Hoyer  discover  the  penetration  of  corneal 
nerves  into  the  epithelium,  366. 

Collective  tubes  of  the  uriniferous  canals  of  the 
kidney,  513. 

Collodium,  143. 

Colloid  (alveolar)  cancer,  285. 

Colloid  degeneration,  285;  of  glands,  415;  of 
the  thyroid,  501. 

Colloid  substances  of  Graham,  122. 

Colophony  dissolved  in  alcohol  as  a  substitute 
for  Canada  balsam,  210. 

Colors,  water,  39 ;  granular  for  injections,  174  ; 
transparent,  177 :  in  tubes,  recommended  by 
Hyrtl  for  injection?,  174. 

Colostrum  corpuscles,  552. 

Columns  Bertini,  505. 

Comedones,  565. 

Concentric  bodies  of  the  thymus,  265,  504. 

Condensers  and  their  effects,  26. 

Cones  of  the  retina,  596.  600,  607. 

Connective  substance,  269 ;  gelatinous,  269 ;  re- 
ticular.  270 :  method  of  demonstrating,  271  ; 
hardening,  271 :  myxomata,  284. 

Connective  tissue,  269,  274:  ordinary.  274;  liv- 
ing, according  to  Kiihne,  275  ;  cells,  275 ;  their 
form,  276 ;  fixed  and  migratory  cells,  276 ;  elas- 
tic elements,  278 ;  pre-existence  of  the  fibril- 
la?,  277 ;  demonstration  of  the  same  by 
chemical  means,  277  ;  double  refracting,  278  ; 
demonstration  of  the  connective-tissue  cor- 
puscles, 275:  methods  of  Banvier  and  Flem- 
ming,  276 ;  elastic  sheath  around  bundles,  279 : 
transformation  of  the  interstitial  substance 
into  gelatine,  280;  impregnation  with  gold, 
281  ;  elastic  fibres,  281 :  embryonic  connective 
tissue,  282 ;  pathological  connective  tissue, 
283  ;  Waller  and  Cohnheim's  investigations, 
283 :  hypertroph'c  connective-tissue,  284  ; 
cicatricial  tissue,  284 :  basis  of  benign  and  ma- 
lignant tumors,  284 ;  forms  of  carcinoma- 
284;  methods  of  examining,  285  ;  cabinet  pre. 
parations,  286. 

Construction  of  the  modern  microscope,  20. 

Contractile  fibre-cells,  314. 

Copal  lac,  205. 


618 


INDEX. 


Copper,  chromate~of,  186,  note;  sulphate,  186, 

note. 

Corium — see  Skin. 
Cornea,  883  ;  nerves  of,  366,  367. 
Corneal  corpuscles,  585. 
Cornil  communicates  the  composition  of    pre- 
servative fluids.  214. 
Corpora    cavernosa  of  male  generative   organ, 

5oT. 

Corpus  Highmori,  553. 
Corpus  lateum.  540,  544. 
Correction  of  the  aberration  of  a  lens,  14,  15  ; 

apparatus  for  objectives,  20,  60. 
Corrosion,  method  for  the  lungs,  489. 
Cortian  organ,  612. 
Cortical  pyramids  of  the  kidney.  510. 
Covering  glass,  thickness  and  "optical  effect  of, 
18,  19  :  correction  for  thickness,  108  ;  manner 
of  applying  the  covering  glass,  206,  222. 
Cowper's  glands,  557. 

Creosote,  144  ;    and    methyl  alcohol,  216  ;    re- 
commended by  Stieda  for  rendering   tissues 
transparent,  144  :  used  by  Schwarz,  159. 
Crouch's  stereoscopic  microscope,  51. 
Crown  glass,  refraction  and  color  dispersion  of, 

11,  12  ;  lenses,  11,  12. 
Cryptococcus  cerevisiae  in  digestive  apparatus, 

433  :  in  the  urine,  532. 
Crystalloid  substances  of  Graham,  123. 
Curtis,  Dr.  E.,  improvement  of  illumination,  90  ; 
improved  section  cutter,  112-117  ;    siibstitute 
for  simple  microscope,  110. 
Curvature  of  microscopic  image,  8,  11. 
Cutaneous  nerves,  369,  370. 
Cutter  on  American  microscopes,  8C-86. 
Cylinder  cells  of  the  regio  olfactoria,  573. 
Cylinder  glasses  for  reagents.  126. 
Cystine  in  the  liver,  474  :  in  the  urine,  534. 
Cysts,  formation  of  in  the  kidney.  524  ;   in  the 
lacteal  glands,  551 ;  in  the  skin,  564. 


D. 

Damar  varnish,  205. 

Dean,  J.,  method  for  examining  the  central  or- 
gans, 355,  note. 

Deane's  mounting  fluid,  211,  216. 
Decalcifying  cartilage,  bones  and  teeth,  292,  299, 

Decidua  of  the  ovum,  549. 
Defining  powers  of  a  microscope,  58. 
Deiters  on  the  cochlea,  611  ;    directions  for  ex- 
amining central  organs  of    nervous  system, 

Delamorph  cells,  427. 

Demodex  folliculorum,  567. 

Dentine,  293,  294  ;  cells  and  their  processes,  294, 
295. 

Descemet's  membrane  of  the  cornea,  583. 

Deyl,  H.  Van,  made  the  first  achromatic  micro- 
scope, 12. 

Dialyser  of  Graham,  124. 

Diaphragms,  25  :  their  effect  on  a  lens,  9  ;  of  the 
compound  microscope,  25  ;  their  use  protects 
the  eyes,  88,  90,  98. 

Diatom  test  plate  of  Holler,  65,  note. 

Diatomacete  as  test  objects,  64  ;  various  sorts 
and  their  resolution,  64-69. 

Digestive  apparatus,  417  ;  material  for  examina- 
tion, 417  ;  lips  with  their  glands,  417  ;  mu- 
cous membrane  of  the  oral  and  pharyngeal 
cavities,  417  ;  papillfe,  glands,  nerves,  vessels, 
417,  418  ;  tongue,  418  :  divisions  of  its  mus- 
cular filaments,  419  ;  blood  and'  lymph  vessels, 
419  ;  tonsils  and  lingual  follicles,  420  :  salivary 
corpuscles,  421  ;  glands,  421  ;  methods  of 
Pfliiger,  Heidenhain,  Krause  and  Ranvier, 
420,  421 ;  submaxillary  gland  in  a  quiet  and 


in  an  irritated  condition,  422,  423  ;  oral  cavity, 
^423;  Leptothrix  buccalis,  424;  Oidium  albi- 
cans,  424  ;  saliva,  425  ;  salivary  corpuscles, 
425  ;  granular  movements  within  them,  425  ; 
oesophagus,  425  ;  stomach,  425  ;  methods, 
425,  426  :  gastric  glands,  426,  427  ;  double  cell 
forms,  427  ;  active  and  inactive  condition, 
427,  428  ;  peptic  gastric  glands,  429  ;  mucous 
membrane,  430  ;  lenticular  glands,  430  ; 
muscles  and  nerves  of  mucous  membrane, 
430  ;  pathological  changes,  430,  431  ;  mamil- 
lated  condition,  431  ;  hypertrophy  of  the  mus- 
cular tissue,  431  ;  vomited  matters,  431-433  ; 
intestinal  canal,  433  ;  cylindrical  epithelium, 
433  ;  becher  cells,  434  ;  methods,  434,  4«5  ; 
Brunner's  glands,  435  ;  Lieberkiihn's  glands, 
434,  437  ;  villi,  438-441  ;  injections,  439,  442  ; 
lymphatics  and  lacteals,  441-444  ;'  lymphatic 
follicles,  solitary  and  Peyerian  glands,  444-448  ; 
vermiform  process,  449  ;  changes  of  the  mu- 
cous membrane,  449 ;  of  the  Peyerian  follicles. 
450  ;  in  abdominal  typhus,  450  ;  preserving 
methods,  451  ;  contents  of  intestines,  451  ;  in 
disease,  452,  453  ;  parasites,  worms  and  their 
ova,  454-457. 

Distoma,   ova  of  in  faeces  (D.  hepaticum  and 
lanceolatum),  456. 

Dollinger's  injections,  171. 

Donders  explains  the  action  of  potash  solutions, 
136  ;  recommends  costal  cartilage,  288. 

Donne  publishes  an  atlas  of  daguerreotypes,  42  ; 
discovers  the  Trichomonas  vaginalis,  548. 

Double  knife  of  Valentin,  111 ;    improved  form 
of  the  English,  111. 

Double     refraction,   weak,  recognition    of    the 
same,  52,  53. 

Drawing  microscopic  objects,  38  ;    methods,  39, 
40  ;  apparatus  for,  40-42. 

Drebbel,  Cornelius,  as  a  discoverer  of  the  com- 
pound microscope,  8. 

Drying  method,  166. 

Ductus  ejaculatorii,  555. 

Dumb-bells  of  uric  acid,  531. 

Dysenteric  stools,  453. 


E. 


berth's  directions  for  preparing  lung  sections, 
490  ;  finds  the  capillaries  composed  of  cells, 
376  :  investigation  of  the  biliary  capillaries, 
464,466. 

Ebstein  on  gastric  mucous  glands,  429. 

Slastic  fibres  in  sputum,  499. 

31ectric  apparatus  of  Harting,  106. 

Elephantiasis.  564. 

Embedding  methods,  117,  118  ;  in  gum,  wax  and 
oil,  paraffin,  glycerine  and  gelatine,  117,  118. 

Emboli,  390,  391. 

Emigration  of  lymphoid  cells  from  the  vessels, 
245,  2S3. 

Enamel — see  Teeth  ;  organ — see  Gelatinous 
Tissue. 

Enchondromata,  290. 

Engelmann  on  the  termination  of  the  nerves 
of  the  voluntary  muscles,  362  ;  on  the  termi- 
nation of  the  gustatory  nerve  of  the  frog,  571. 

Epidermis,  261. 

Epididymis.  553  ;  its  ciliated  cells,  553. 

Epiphytes,  565. 

Epithelial  cancer.  265,  285. 

Epithelium,  251 :  pavement,  cylinder,  ciliated 
and  pigment.  251 :  demonstration,  253 ;  simple 
pavement,  253 ;  silver  impregnation.  254 ;  ex- 
amination of  the  pigmented  cells,  254 :  mole- 
cular move  nent  of  the  pigment  granules,  255 ; 
cylinder,  255  ;  porous  canals  on  cylinder  cells, 
256;  methods  of  preserving,  257;  ciliary 
movement,  257:  fluid  media  and  choice  of 


INDEX. 


619 


materials.  357,  358 :  movement  reproduced  by 
dilute  alkalies,  259 :  forms  of  the  movement 
according  to  rnrkinje,  Valentine  and  Engel- 
mann,  260;  obtaining  ciliated  cells  in  acute 
catarrh  of  the  nose  and  respiratory  passages, 
260 :  stratified  pavement,  epithelium  and 
epidermis,  2<il ;  stachel  and  riff  cells,  261: 
action  of  alkalies,  262 :  chloride  of  gold,  263 ; 
epithelial  new  formations  of  a  pathological 
nature,  265;  indurations  and  warts,  265; 
pearl-like  tumors  and  concentric  bodies  of  the 
thymus,  265. 

Epizoa,  567. 

Ether  dissolves  fat  and  Canada  balsam,  143. 

Eustachian  tube.  609. 

Examination  with  the  microscope,  87;  with 
magnifying  powers  of  increasing  strength,  92, 
93. 

Exostosis,  309. 

Exudation  cylinders  of  the  uriniferous  canals  in 
Bright's  disease.  524  ;  in  the  urine,  527. 

Exudations,  asserted  organization  of,  283. 

Eye,  see  Organs  of  Vision,  579 ;  hypermetropic, 
3  ;  myopic,  3 ;  as  a  camera  lucida,  1 ;  protect- 
ing the,  89,  97. 

Eyeball,  581 ;  lids,  579. 

Eye-piece  micrometer,  36 ;  valuation  of  its  di- 
visions, 36,  37 ;  dependence  of  the  same  on 
the  objectives,  36;  with  screw,  34;  improved 
by  Motil,  S5. 

Eye-pieces  of  the  oldest  compound  microscopes, 
7 ;  of  the  improved  instruments,  14  ;  designa- 
tion according  to  their  strength,  15  ;  shorten- 
ing with  the  increase  in  strength,  16  ;  ordinary 
negative  of  Huyghens,  16  ;  positive  of  Rams- 
den,  17  ;  orthoscopic  of  Kellner,  16.  94 ;  ho- 
losteric,  16 ;  aplanatic,  17  ;  under  corrected, 
18;  position  of  the  lenses  in  an' eye-piece,  18 ; 
use  of  weak  eye-pieces,  93 ;  limits  of  their 
application,  93;  uselessness  of  very  strong 
ones,  93,  94. 

F. 

Farrant's  mounting  fluid,  212. 

Fat  emboli  in  the  capillaries,  390. 

Fat  tissue,  273 ;  demonstration.  273.  274 ;  crys- 
tallization of  contents  of  cell,  274;  blood- 
vessels of,  274 ;  mounting,  274  ;  new  formation 
as  lipoma,  284. 

Fattv  acids,  crystals  of,  in  pus,  250  ;  in  fat  cells, 
274. 

Fatty  liver,  470. 

Favus  fungus,  566. 

Fermentation  of  pus,  250 ;  of  the  urine,  529, 
522 ;  alkaline,  533. 

Fermentative  fungus  in  stomach,  533;  in  acid 
urine,  532 :  in  alkaline,  533. 

Ferro-cyanide  of  copper,  186,  note ;  of  potash, 
178,  179, 184. 

Fibre  cells,  contractile — see  Muscles. 

Fibrin,  226,  assumed  organization  of,  283. 

Fibroid,  consisting  of  connective  tissue,  284,  of 
the  uterus.  547. 

Field,  importance  of  shading  the,  88.  98. 

Flakes  containing  blood  corpuscles  in  the  spleen, 
482. 

Flint  glass,  refraction  and  color  dispersion  of, 
11 ;  lenses,  11.  52. 

Fluid  media  for  microscopic  preparations,  120  ; 
indifferent,  121-124:  more  active  ones,  124; 
their  optical  effects,  120,  121 ;  their  preserva- 
tion by  means  of  camphor.  124 ;  crystalloid 
and  colloid  matters,  122 ;  iodine-serum,  124. 

Follicular  chains  of  the  ovary,  of  Pfluger,  543. 

Follicular  tumors  of  the  skin,  564. 

Food,  remains  of,  in  saliva,  423 ;  in  vomited 
matters,  431,  432 :  in  small  intestines,  451, 
452 ;  in  fasces,  452,  453. 


Forceps,  109. 

Forked  cells  of  the  lingual  papillae,  571. 

Formic  acid  in  combination  with  glycerine,  re- 
commended by  Ranvier  as  a  mounting  fluid, 
211. 

Forster  isolates  bone  corpuscles  with  strong 
mineral  acids,  293. 

Fovea  centralis  of  the  retina,  607. 

Freezing  method  for  obtaining  fine  sections,  168. 

Frerichs  on  liver  diseases,  469. 

Frey,  testing  lenses,  71 ;  recommends  anilin  red 
for  tingeing,  155 ;  and  for  the  axis  cylinder, 
334;  anilin  blue,  156;  luematoxylin,  158; 
cold  flowing  injection  mixtures,  181,  185; 
carmine  for  injections,  181 ;  sulphate  of  bary- 
ta, 177,  185;  directions  for  a  watery  Prus- 
sian blue  for  injecting  glandular  canals,  186, 
note ;  very  dilute  acetic  acid  for  muscular 
nerves,  134,  3(53  ;  on  biliary  capillaries,  464 ; 
on  absence  of  lymphatics  in  the  thymus,  502 ; 
on  lymphatics  of  the  trachoma  glands,  580  ; 
on  injections  of  the  uriniferous  canals,  516. 

Frustulia  Saxonica  as  a  test  object,  65. 

Fuchsin — see  Anilin  Red. 

F'uhrer  recommended  chloride  of  iron  for  hard- 
ening spleen,  139. 


Ganglion  cells— see  Nervous  System  ;  layer  of, 
of  the  retina,  596,  603. 

Gas  chamber  of  Strieker,  104. 

Gastric  carcinoma  (false),  431. 

Gastric  glands,  426,  429. 

Gcgenbaur's  osteoblasts,  303. 

Gelatine  as  an  injection  mass,  171 ;  with  glyce- 
rine, 211 ;  varieties  of,  171. 

Gelatinous  tissue,  269;  vitreous  body,  269; 
enamel  organ,  270 ;  new  formations,  myxoma, 
284. 

Generation,  female  organs  of,  539  ;  structure  of 
the  ovary,  its  stroma  and  follicles,  539,  540 ; 
the  ovum,  540 ;  its  constituents  and  the 
methods  for  its  investigation,  540,  541  ;  the 
germ,  542  ;  development  of  the  follicle,  543  ; 
rupture  of  the  follicle,  544  ;  formation  of  the 
corpus  luteum,  545 :  crystals  of  haematoidine 
in  it,  545;  pathological  conditions  of  the 
ovary,  545,  546  ;  ovarial  cysts,  545 ;  with  the 
structure  of  the  skin,  546 ;  oviducts,  546  ;  ute- 
rus, 546 :  mucous  membrane  arid  glands.  546 ; 
muscular  portion,  546 ;  pathological  conditions 
of  the  uterus,  547:  fibroid  tumors*  polypi 
and  carcinomata,  547;  vagina  and  external 
genitals,  547;  secretion  of  the  cervix  uteri, 
548 ;  vaginal  mucus,  548 ;  Trichomonas 
vaginalis,  548;  menstrual  blood,  549;  lochial 
secretion,  549 ;  lacteal  glands,  550 ;  develop- 
ment, 550  ;  pathological  conditions,  551 ;  cysts 
and  adenoid  tumors,  551 :  methods  of 
examining  the  organ,  551 ;  milk,  551 ;  colos- 
trum corpuscles,  552 ;  methods  of  examining 
the  milk,  552. 

Generation,  male  organs  of,  553;  testicles, 
seminte  canalicules,  corpus  Highmori,  epididy- 
mis,  553 ;  blood-vessels,  553 ;  lymphatics,  554 ; 
pathological  new  formation  of  the  testicle, 
555;  methods  of  injection  and  examination, 
555  ;  ductus  ejaculatorii,  555  ;  prostate,  556  ; 
its  concretions,  556 ;  Cowper's  glands,  557 ; 
cavernous  organs,  557 ;  seminal  filaments, 
557 ;  movements,  action  under  reagents,  557, 
558 ;  development,  558,  559 ;  preserving  the 
filaments,  559;  recognition  of  the  same  in 
seminal  stains,  559. 

Gerlach,  photographing  apparatus  of,  43,  45  ; 
increase  of  magnifying  power  by  means  of 
photography,  48 ;  inventor  of  carmine  tinge- 


620 


INDEX. 


ing,  150;  on  application  of  chloride  of  gold 
and  potash,  355  ;  carmine  injection,  181 ;  bone 
injection  208 ;  method  of  examining  the  tac- 
tile bodies,  371 ;  of  injecting  the  seminal  ca- 
nals, 555. 

Germinal  vesicle  and  spot,  see  Ovum. 

Gianuzzi  on  the  submaxillary  gland,  422. 

Glands,  394;  lymphatic,  394-403;  structure, 
membrana  propria,  cells  and  vessels.  403,  404 ; 
tubular  glands,  403;  coil-shaped,  405 ;  race- 
mose, 405,  406 :  their  capillary  network,  405  ; 
closed  gland  capsules,  406,  408  ;  of  the  ovary, 
407 ;  blood  vascular  glands,  408 ;  thyroid 
gland,  408  ;  lymphoid  glands,  408:  gland  cells, 
409 ;  their  origin,  409 ;  perishable  nature, 
410;  formation  of  the  secretion,  410;  injec- 
tions, 413;  examination  of  foetal  glands,  413, 
414 ;  pathological  changes,  414,  415 ;  partici- 
pation of  the  framework,  414 ;  new  formation 
of  gland  tissue,  416. 

Glands,  coil-shaped,  of  the  conjunctiva,  579 ;  of 
the  auditory  organ?,  609. 

Glass  boxes,  quadratic,  108;  cells,  218,  219. 

Glioma  of  the  brain,  358;  of  the  retina,  608. 

Glycerine  as  a  medium  for  rendering  tissues 
transparent,  121 :  index  of  refraction,  121  ; 
for  moist  mounting,  210 ;  with  water  and  mu- 
riatic acid,  211 ;  with  acetic  acid,  211  ;  formic 
acid,  211 ;  carbolic  acid.  212  ;  gelatine,  117, 
211,  280 :  gum-arabic  and  carbolic  acid,  212  ; 
carmine.  152,  154. 

Goad  by 's  fluid,  212,  213. 

Goitre,  502. 

Gold,  chloride  of,  140,  163, 164 ;  and  potash,  140, 
165,  355. 

Gold  size,  223. 

Goniometer  of  C.  Schmidt,  38. 

Goodsir,  J.,  discovers  sarcina  ventriculi,  433. 

Graafian  follicle  of  the  ovary,  539. 

Graham  on  colloid  and  crystalloid  substances, 
122. 

Grammatophora  subtilissima,  64,  65,  68. 

Granulations,  284 ;  in  Bright's  disease,  525. 

Granule  cells,  498. 

Grindstone,  rotary,  118. 

Growths,  horny,  of  the  skin,  265. 

Grunow,  J.,  sketch  of,  83. 

Gum,  with  glycerine,  212;  for  embedding,  117  ; 
as  an  addition  to  chromic  acid,  132. 

Gustatory  organ,  569  ;  nerve  distribution,  569  ; 
discovery  of  the  nerve  termination  in  the 
papilla?  of  the  frog's  tongue,  by  Schultze  and 
Key,  570 ;  gustatory  cells,  570  ;  forked  cells  of 
Engelmann,  571. 

Gutta  percha  cement,  220 ;  cells,  218. 


H. 


Hackel  recommends  crabs  for  the  demonstration 
of  the  sarcous  elements  of  striated  muscles, 
325. 

Ha?matine  crystals,  239. 

Haemato-crystalline,  237. 

Haematoidine  crystals,  241 ,  in  ruptured  Graafian 
follicles,  545. 

Hasmoglobine  crystals,  237. 

Hagen  on  American  microscopes,  80. 

Hair,  265  ;  method  of  examining,  2(55,  268 :  foetal, 
208 ;  in  dermoid  cysts  of  the  ovary,  546  ;  dis- 
eases, see  Skin;  fungi,  565;  hair-sac  mite, 
566. 

Hannover  recommends  chromic  acid,  120. 

Hardening  by  chromic  acid,  130  ;  bichromate  of 
potash,  139 ;  alcohol,  140  ;  freezing,  168. 

Harting  investigates  the  qxiestion  of  the  inven- 
tion of  the  compound  microscope,  8 ;  explains 
the  action  of  the  immersion  system,  61 ;  electric 
apparatus,  106 ;  recommends  weak  solutions  of 


sublimate  for  preserving,  214 :  chloride  of  cal- 
cium, carbonate  of  potash,  and  creosote.  215  ; 
on  the  refractive  power  of  fluid  media,  120  ; 
directions  for  making  chrome-yellow  and  chro- 
mate  of  lead,  176 ;  Prussian  blue  in  oxalic 
acid,  179;  of  sulphate  of  iron  and  ferro-cya- 
nide  of  potash,  179;  tin  case  for  injecting, 
192 ;  gutta-percha  cement,  221 ;  india-rubber, 
221. 

Hartnack,  his  holosteric  eye-piece,  16;  stereo- 
scopic, 51 :  improves  polarizer  and  analyzer, 
52 ;  lenses  and  their  angles  of  aperture,  76  ; 
immersion  systems,  60 ;  microscopes,  76,  77  ; 
lamp,  90. 

Hassal's  concentric  bodies  of  the  thymus,  265. 

Heart,  branched  muscular  fibres  of,  310. 

Heidenhain,  bis  method  of  staining  with  car- 
mine, 155 :  anilin  blue,  157 ;  on  cai-tilage  cor- 
puscles. 289 ;  on  salivary  glands,  421,  423  ;  on 
gastric  glands,  427,  428. 

Helminthian  ova  in  the  ffeces,  455. 

Henle  recommends  strong  muriatic  acid  for  the 
uriniferous  canals  of  the  kidney,  129 ;  method 
of  obtaining  transverse  sections  of  the  hair, 
268 ;  investigates  the  course  of  the  urinifer- 
ous canals,  506. 

Henson,  his  section-cutter,  112;  on  the  termi- 
nation of  nerves  in  tail  of  frog's  larvae,  368, 
373. 

Bering's  apparatus  for  injecting  with  constant 
pressure,  192. 

Herpes  tonsurans,  565. 

His,  brushing  method,  118;  silver  impregna- 
tion, 140,  160 ;  adenoid  tissue,  270  :  perivascu- 
lar  space,  357;  on  the  cornea,  584;  on  the 
thymus,  502. 

Hoffman's  indicator,  226,  note. 

Holosteric  eye -piece,  16. 

Hordeolum  (milium),  565. 

Hoyer.  his  yellow  transparent  coloring  matter, 
183  ;  and  Cohnheim  discover  the  penetration 
of  corneal  nerves  into  the  epithelium,  366. 

Huyghen's  negative  eye-piece.  16. 

Hyaloidiscus  subtilis,  recommended  by  Bailey 
as  a  test  object,  65. 

Hypertrophies,  see  the  several  organs. 

Hypophysis  cerebri,  374. 

Hypoxanthine  (or  sarcine)  in  the  liver,  473  ;  in 
the  urine,  535. 

Hyrtl,  history  of  injections,  170 ;  on  resinous 
masses,  171,  173 ;  cold-flowing  mixtures,  173  ; 
recommends  colors  in  tubes,  174 :  puncturing 
method,  197 ;  investigation  of  the  kidney,  507, 
518. 


I. 


Illuminating  apparatus  of  Dujardin,  26 ;  of  Lie- 
berkuhn,91. 

Illuminating  lens  for  opaque  objects.  24. 

Illumination  by  incident  light,  24 :  by  trans- 
mitted, 24,  91 ;  by  artificial,  89,  90,  91 ;  by 
central,  88 ;  by  oblique,  89  ;  with  cylindrical 
and  rotary  diaphragms,  25  ;  with  a  condenser, 
26  ;  of  the  field  depends  on  the  condition  of  the 
sky,  88 ;  method  of  improving,  used  by  Dr. 
Curtis,  90. 

Image,  aerial,  of  the  compound  microscope,  7,  8. 

Image  distortion,  10. 

Image-inverting  microscope,  100. 

Image  of  the  compound  microscope,  6,  8 ; 
clearness  of  the  same  increased  by  the  field- 
glass,  13,  15 ;  curved,  of  the  simple  compound 
microscope,  8 ;  enlarged,  7 ;  inversion  of  the 
same  by  the  microscope,  6. 

Images,  microscopic  peculiarities  of,  98 ;  their 
relations  of  height  and  depth,  98,  99  :  judg- 
ing of  the  form  from  these,  99 ;  value  of  weak 


INDEX. 


621 


objectives  thereby,  99 ;  increased  difficulty  of 
their  appreciation  from  extreme  diminutive- 
ness  of  the  bodies,  90 ;  appreciation  of  their 
relations  of  relief,  99 ;  Welcker's  directions  for 
this  purpose,  99. 

Immersion  lenses,  60. 

Indicator  (object-finder),  225. 

Indigo  carmine,  157. 

Indurations,  265. 

Infarction,  hemorrhagic  of  the  spleen,  485. 

Inflammatory  globules,  498. 

Infundibula  of  the  lungs,  489. 

Injection  methods  for  blood-vessels,  194,  195  ; 
for  lymphatics,  195;  by  puncture,  197;  of 
parts  with  thin  walls,  198  ;  of  glandular  pas- 
sages, 196 ;  minutiae  of  the  procedure,  197- 
200 ;  double,  200,  201 ;  of  blood,  and  lympha- 
tic vessels,  201 ;  subsequent  treatment  of  in- 
jected preparations,  201,  202;  methods  of 
preservation,  203;  of  the  brain  and  spinal 
cord,  b'56 ;  for  glandular  passages,  186,  note  ; 
spontaneous  of  the  living  animal,  197;  with 
carmine  and  indigo  carmine,  187,  1 88 ;  of  the 
lymphatics  with  anilin  blue,  by  Toldt,  398  ; 
with  constant  pressure,  188-192. 

Injections,  importance  of  for  histological  inves- 
tigations, 169 ;  the  art  in  its  infancy,  170  ;  in 
its  present  condition,  170 ;  colors  for :  granular, 
formed  by  precipitations  in  the  vessels,  173  ; 
colors  in  tubes,  174 ;  red,  cinnabar,  175  ;  yel- 
low, chrome  yellow,  175 ;  white,  lead  and  zinc 
white,  sulphate  of  baryta,  176,  177 ;  chloride 
of  silver,  177;  transparent,  177;  Thiersch's 
Prussian  blue,  118  ;  Prussian  blue  in  oxalic 
acid,  178, 179;  other  varieties  ol  Prussian  blue, 
179,  180,  183-185  ;  Gerlach's  carmine  mass, 
181;  Prey's  method,  181,  182;  Thiersch's 
transparent  yellow,  182  ;  of  Hoyer,  183 ; 
Thiersch's  transparent  green,  183;  Beale's 
blue  for  cold  injections,  183,  184  ;  Richard- 
son's, 184 ;  Miiller's,  185 ;  Beale's  carmine, 
185  ;  Frey's  baryta,  185,  186. 

Instruments  for  making  microscopic  prepara- 
tions, 108-112. 

Intercalary  piece  in  the  cortex  of  the  kidney, 
514. 

Intestinal  contents,  451 ;  ganglia,  342,  343,  344 ; 
glands,  434,  435  ;avilli,  438,  439. 

Intestines,  433. 

Introduction  to  microscopic  work,  87. 

Inversion  of  the  microscopic  image,  6,  7. 

Iodine,  136 ;  with  sulphuric  acid,  its  action  on 
amylon,  amyloid,  cellulose,  and  cholesterine, 
127. 

Iodine  serum  of  Schultze,  124. 

Iris,  589. 

Iron,  chloride  of,  139,  180,  183,  184  ;  sulphate 
of,  for  making  Prussian  blue,  179,  184. 

Itch,  the,  567. 


J. 


Janssen,  Zaccharias,  inventor  of  the  compound 
microscope,  8. 


K. 

Kidneys,  505. 

Knives,  109. 

Kolliker  recommends  dilute  acetic  acid  for  mus- 
cular nerves,  134,  363 ;  on  cytogenous  tissue, 
270 ;  recommends  boiling  the  thymus,  5u4  ; 
studies  the  lymphatics  in  the  tail  of  the  frog's 
larva,  403 ;  examined  with  Scanzoni  the  mu- 
cus of  the  female  genital  organs,  548. 

Kollmann's  carmine  injection  fluid,  186,  note. 

Krause,  W.,  recommends  dilute  acetic  acid  for 
muscular  nerves,  364 ;  discovers  the  terminal 


knobs,  369;  recommends  acetic  acid  for  the 
latter,  369 ;  uses  molybdenate  of  ammonia  for 
the  salivary  glands,  421,  422. 
Kiihne  recommends  dilute  sulphuric  acid  for 
muscular  nerves,  364  ;  nitric  acid  and  chlorate 
of  potash  for  isolating  muscular  fibres,  319  ; 
investigation  of  the  cornea,  586. 


Lacteals,  441. 

Lambl's  cercomonas  intestinalis,  454. 

Lamina  elastica  an<  erior  of  the  cornea,  583  ;  of 
the  choroid,  591 ;  spiralis  of  the  cochlea,  609. 

Landois  uses  fuchsin  for  cartilage,  289. 

Lardaceous  liver,  475. 

Larynx,  487. 

Leber's  impregnation  with  Prussian  blue,  166. 

Legros  uses  hyposulphite  of  soda  for  objects  im- 
pregnated with  silver,  161. 

Lehmann  on  crystals  of  muriate  of  haematine, 
239. 

Lens  (double)  achromatic,  of  crown  and  flint 
glass,  11 ;  first  applied  to  the  microscope  by 
Van  Deyl  and  Fraunhofer,  12  ;  aplanatic,  11, 
17,  18;  over  and  under  corrected,  12. 

Lens  of  the  eye,  592 ;  changes  in  disease,  595  ; 
development  of,  595. 

Lenticular  glands,  430. 

Leptothrix  buccalis,  424  ;  in  fasces,  453. 

Leucasmia,  232. 

Leucine  from  the  liver,  472 ;  in  urine,  535. 

Lieberkiihn's  apparatus  for  illumination,  91  ; 
glands,  434,  437. 

Light,  central  and  oblique,  25,  26,  88,  89 ;  polar- 
ized, 52-54 ;  moderation  of  the,  88,  98 ;  artifi- 
cial, moderated  by  blue  glasses,  90. 

Lime,  carbonate  of.  crystals  suitable  objects  for 
study  of  molecular  movement,  101 ;  in  the  or- 
gan of  hearing,  610  ;  oxalate  of  in  urine,  532 ; 
in  the  exudation  cylinders  of  Brights  disease, 
525,  526  ;  lime-water  used  by  Rollett  for  con- 
nective tissue,  137  ;  infarctions  of  the  kidney, 
526. 

Line,  Paris,  reduced  to  millimetres,  36. 

Lingual  follicles,  420. 

Lipoma,  273,  284. 

Lips  and  their  sebaceous  follicles,  417. 

Liquid  stove-polish,  a  substitute  for  Brunswick 
black,  223. 

Lister  and  Turner  on  the  inner  circle  of  the 
transverse  section  of  the  nerve  tube,  335. 

Liver,  459;  cells,  459;  lobules,  460;  methods  of 
demonstration,  460,  461 ;  blood-vessels  and  in- 
jections, 461 ;  capillary  networks  and  their 
cells,  461 ;  membrana  propria,  463  ;  finest 
biliary  passages,  464 ;  their  injection,  etc., 
464,  467;  lymphatics,  468;  nerves,  468; 
bile,  468,  469;  pathological  changes  of  liver, 
469;  hypertrophy,  469;  pigmentation,  470; 
deposition  of  fat  and  fatty  degeneration, 
470,  471 ;  destruction  of  the  liver  in  acute  yel- 
iow  atrophy,  471  ;  chemical  constituents  of 
the  diseased  liver,  472  ;  tyrosine,  leucine.  hy- 
poxanthine  (sarcocine),  xanthine,  cystine, 
472-475  ;  emboli  of  the  hepatic  vessels  by  pig- 
ment flakes  in  melana;mia,  475;  amyloid  de- 
generation (waxy  or  lardaceous  liver),  475  ; 
tubercles,  476  ;  cirrhosis,  477  ;  carcinoma,  477. 

Lochial  secretion,  549. 

Loupe,  4  ;  stand,  4,  5. 

Ludwig  and  Tomsa  on  the  lymphatics  of  the 
testicle,  554  ;  L.  and  Zawarykin  on  the  kid- 
neys, 507. 

Lungs,  487  ;  vesicles  of,  489-491  ;  epithelium, 
490,  491  ;  fibres  of  in  sputum,  499  ;  capillary 
loops,  491. 

Lymph,  246 ;  cells  (corpuscles),  246,  247 ;  mount- 


622 


INDEX. 


ing,  247  ;  in  the  mucous  membrane  of  the  in- 
testines, 436  ;  in  spleen,  481-483  ;  of  thymus, 
502. 

Lymphatic  glands,  394  ;  methods  of  examina- 
tion, 394,  395  ;  Toldfs  method,  395  ;  frame- 
work, 396  ;  injections,  396,  397  ;  puncturing 
method,  397  ;  natural  injection,  398  ;  patho- 
logical changes,  399  ;  fatty  degeneration.  399 ; 
pigmentations,  399  ;  of  bronchial  glands,  399, 
400  ;  connective-tissue  metamorphosis,  400  ; 
conditions  in  abdominal  typhus,  400,  401  ;  in 
tuberculosis  and  scrofula,  401  ;  inflammatory 
conditions  and  hypertrophies,  401,  402 ;  value 
of  injections  in  these  cases,  402  ;  develop- 
ment in  the  foetus,  403. 

Lymphatics,  393  ;  structure  and  examination 
of  the  larger  and  smaller  trunks  and  lacunae, 
393  ;  silver  impregnation,  393  ;  injection,  394  ; 
lacteals,  394  ;  new  formation  of  lymphatics 
in  neoplasms,  according  to  Krause,  394. 

Lymphoid  cells,  246,  247. 


Maceration  in  acids  of    connective  tissue.  278, 
279  ;  of  bones  and  teeth,  293,  294,  300  ;  of  the 
muscles,  314,  319,  320  ;    of   the  kidneys,  511, 
512. 
Magnesium  light  fcr  photographing,  46. 

Malmsten's  paramajcium  coli,  454. 

Malpighian  vascular  coil  of  the  kidney,  518  ;  cor- 
puscles of  the  spleen,  481  ;  pyramids  of  the 
kidney,  505  ;  rete  mucosum  of  the  skin,  561. 

Mammiliated  condition  of  the  gastric  mucous 
membrane,  431. 

Marine  glue,  220. 

Mask  lack,  black,  224. 

Mastic,  171,  205. 

McAllister  on  American  microscopes,  80. 

Measures,  microscopic,  37,  38. 

Measuring  apparatus,  microscopic,  34,  38. 

Meconium,  453. 

Medullary  rays  of  the  kidney,  509. 

Meibomian  glands,  579. 

Melantemia,  2o2 ;  condition  of  the  liver  and 
spleen  in,  475  ;  cerebral  vessels,  391  ;  emboli 
of  the  hepatic  vessals,  475  ;  of  the  kidneys, 
523. 

Melanine,  251,  590. 

Melanosis  (and  anthracosis)  of  the  bronchial 
glands,  398,  399  ;  of  the  lungs,  492,  493. 

Membrana  hyaloidea,  595. 

Membrana  limitans  externa  of  the  retina,  600  ; 
interna,  600. 

Membrana  propria — see  Glands. 

Menstrual  blood,  549. 

Mentagru,  566. 

Mercury,  chloride  of,  140,  213,  214  ;  with  alum 
and  chloride  of  sodium,  213. 

Mercury,  column  of,  for  injecting,  189,  190. 

Metallic  impregnations,  160  ;  nitrate  of  silver, 
160,  161  ;  osmic  acid,  162,  163  ;  osmiamide, 
163  ;  chloride  of  gold,  1(53,  164  ;  and  potash, 
165 ;  chloride  of  palladium,  165  ;  Prussian 
blue.  166. 

Methyl  alcohol,  143  ;  as  a  constituent  of  cold 
flowing  inj  ection  mixtures,  184  ;  of  preserva- 
tive fluids,  216. 

Meyer.  H.,  recommends  sulphuric  acid  for  sepa- 
rating the  epidermoid  covering  of  the  hair, 
266,  267. 

Mica  scales,  54. 

Micrometer  screw,  24. 

Micrometers,  33,  37. 

Micromillimetre,  37. 

Microscope,  compound,  selection  of,  71 ;  arrange- 
of,  13  ;  simplest  form  of,  6,  8 ;  improved  form, 
12 ;  tube,  23  ;  objectives,  13,  16,  20  ;  eye- 


pieces, 16,  18,  21 ;  mirror,  24  ;  diaphragms.  25 ; 
condensers,  26 ;  use  of  the  instrument,  87  ; 
illumination,  87,  91  ;  adjustment,  92  ;  care  in 
the  use  of  reagents,  94  ;  cleaning  the  glasses, 
95  ;  testing,  55  ;  the  magnifying  power,  55  ; 
the  spherical  and  chromatic  aberration,  56  ; 
the  flatness  of  the  field,  57  ;  defining  power, 
58  ;  penetrating  power,  58,  59  ;  value  of  the 
optical  portion,  73,  74 ;  of  the  mechanical  por- 
tion, 73. 
Microscope,  its  importance  for  the  physician,  vii ; 

literature  of ,  x. 
Microscope  lamps,  90. 

Microscope,  oldest  compound,  its  discovery,  8. 
Microscope,  simple,  4,  6  ;  its  arrangement  (stand, 
stage,  mirror,  &c.),  4,  6  ;    Dr.   Curtis1  substi- 
tute for,  110. 

Microscopes,  American,  80,  86. 
Microscopes,  compound  binocular,  49,  50  ;    mul- 
tocular, 50  ;  photographic,  43  ;  polarizing,  51, 
52  ;  stereoscopic,  50,  51 . 
Microscopes  of  various  makers,  77,  80  ;  American, 

80-86. 

Microscopic  vision,  viii,  88,  98. 
Microscopist,  qualifications  of  the,  96. 
Microsporon  audouini,  565 ;  mentagrophytes,  5G6; 

furfur,  566. 
Miliary  tubercle  of  the  cerebral  vessels,  373  ;  of 

the  spleen,  485  ;  of  the  lungs,  494. 
Milium,  565. 

Milk,  551 ;  globules.  552  ;  glands,  550  ;  new  for- 
mations of,  551. 
Miller,  L.,  notice  of,  85. 

Millimetre  reduced  to  Paris  lines,  &c.,  37,  38. 
Mineral  acids,  127. 

Mirror  of  the  simple  microscope,  6  ;  of  the  com- 
pound microscope,  with  a  plane  surface,  24, 
88  ;  with  a  concave  surface,  24,  88. 
Mixture  of  Muller,  139  ;  of  Goad  by,  212,  213  ; 
of  Pacini,  213;  cold  flowing  for  injections,  171, 
183-185. 

Moitessier  on  micro-photography,  43  ;  his  photo- 
graphic apparatus,  45. 

Moleschott  recommends  a  strong  and   a  weak 
mixture  of  acetic  acid  and  alcohol,  142  ;    pot- 
ash solutions,  137  ;  investigates  the  action  of 
potash  solutions  on  epithelium,  262. 
Moller's  preparations,  227  ;  diatonic  test  plate, 

65,  note. 

Mother  cells  in  cartilage,  288. 
Mould  formation  in  urine,  532,  533. 
Mounting  media,  205  :  resinous,  205-210  ;  fluid, 

210  ;  simple,  210  ;  compound,  211,  216. 
Movement  phenomena  vital,  1GO  ;    amoeboid  of 
the  cells,  102  ;    of    small    bodies,  100  ;    mole- 
cular, 101. 

Mucous  coi-puscles,  247  ;  origin,  &c.,  247 :  of  the 
oral  cavity  (salivary  corpuscles),  425  ;  in  vom- 
ited matters,  432  ;  in  small  intestine,  434  ;  in 
the  evacuations  of  pyrosis  and  cholera,  4:32,  453; 
in  sputum,  496  ;  in  freces,  453  ;  in  urine,  526, 
528  ;  in  the  vaginal  mucus,  548  ;  in  nasal 
mucus,  573. 

Mucous  glands  of  the  mouth  and  pharynx.  417  ; 
of  the  nose,  572  ;  of  the  small  intestines,  nee 
Brunner's  Glands  ;  submaxillary  as  a  mucous 
gland,  422. 

Mucous  membrane  of  the  digestive  organs,  418, 
426,  436-439  ;  of  the  respiratory  organs,  487  ; 
of  the  bladder,  526  ;  of  the  nose,  572. 
Mucus,  247. 
Muguet  (thrush),  424. 
Miiller,  H.,  and  Samisch's  investigation  of  the 

corneal  nerves,  367. 

Muller,  W.,  his  Prussian  blue,  185;  brown  in- 
jection fluid,  186,  note  ;  studies  on  the  spleen, 
483. 

Muller's  fluid,  129. 
Multipolar  ganglion  cells — see  Nervous  System. 


INDEX. 


623 


Muriatic  acid,  129. 

Muscles,  312  ;  smooth  and  striated,  312  ;  method 
of  examining  the  smooth,  318,  314  ;  contrac- 
tile fibre  cells,  314  ;  their  isolation,  314,  315  ; 
degeneration  and  new  formation,  315  ;  striated, 
315  ;  methods  of  examination,  316,  317  ;  nu- 
cleus and  sarcolemrna,  317  ;  relations,  318  ; 
isolation  of  the  filaments,  319  ;  chemical  ac- 
cessories, 31!),  320  ;  relation  to  the  tendons, 
321  ;  method  of  demonstration,  321  ;  pointed 
filaments,  322  ;  capillaries,  322  ;  nerve  termi- 
nations— aee  Nervous  System  ;  explanation  of 
the  longitudinal  and  transverse  markings, 
323  ;  sarcous  elements,  324 ;  study  of,  with 
reagents,  326;  double  and  single  retracting 
strata,  accord  ing  to  Briicke,  327;  development, 
328  ;  fatty  degeneration,  328 ;  pathological 
changes,  328,  329 ;  typhus  metamorphosis,  ac- 
cording to  Zenker,  329  ;  trichina,  329  ;  their 
capsules,  &c.,  329,  330  ;  mounting  prepara- 
tions, 330. 

Muscular  fibres  in  vomited  matters,  432  ;  in 
fteces,  452. 

Myeline,  359. 

Myxoma,  284. 

N. 

Nasvi,  vascular,  564. 

Nail  fungus,  565. 

Nails,  204  ;  with  alkalies  and  sulphuric  acid, 
264. 

Nasal  catarrh,  572,  573. 

Nasal  mucous  membrane,  572. 

Navicula  affinis,  65,  69.  note  ;  Amicii,  65,  69, 
note  ;  rhomboides  (sporangial  form),  69. 

Near  point,  2,  3. 

Needles,  109. 

Negative  eye-piece  (Huyghenian),  16. 

Negative,  photographic,  48. 

Nerve  corpuscles  of  the  genitals,  563. 

Nervous  system,  331  ;  elements  of,  331  ;  nerve 
fibres,  Sol  ;  ganglia  or  nerve  cells,  331  ;•  con- 
stituents of  the  nerve  fibres  :  axis  cylinder, 
medulla,  primitive  sheath,  331  ;  suitable  lo- 
calities for  examination.  331  ;  homogeneous 
nerve  fibres,  331  ;  coagulation  of  the  medulla, 
832  :  action  of  reagents,  333  ;  axis  cylinder, 
333  :  reagents  and  media,  333-335  ;  sections 
of  hardened  nerves,  335  ;  concentric  circles, 
335  :  axile  or  primitive  librilhu,  335  ;  non- 
medullated  fibres  of  the  olfactory  nerve,  336  ; 
Kemak's  fibres,  337  ;  embryonic  nerve  fibres, 
337  :  method  of  examination,  337  ;  by  polar- 
ized light,  337  ;  ganglion  cells,  338  ;  appear- 
ance, 338  ;  processes,  338  ;  apolar  cells,  339  ; 
methods,  339,  341 ;  Beale  and  Arnold  on,  342 ; 
ganglia  in  the  sub-mucous  tissue  of  digestive 
canal,  343  ;  plexus  myentericus  of  Auerbacb. 
343-345  ;  methods,  843-345  ;  central  organs 
of  the  nervous  system,  brain  and  spinal  cord  ; 
examination  of  in  a  fresh  condition,  346 ; 
nerve  fibres.  346  ;  multipolar  ganglion  cells, 
346-349  ;  methods,  346-349  ;  complex  struc- 
ture of  the  ganglion  cells,  349,  350  ;  methods, 
349-355  ;  injections,  356  ;  peri  vascular  space 
of  His,  357  ;  connective-tissue  frame-work 
(neuroglia),  357  ;  occurrence  of  in  the  brain 
and  spinal  cord,  357,  358  ;  amyloid  bodies,  358  ; 
myeline,  359  :  cholesterine,  359,  360  ;  nerve 
terminations,  360  ;  of  motor  nerves  in  striated 
muscles,  360 ;  material  and  methods,  361-364  ; 
isolation  of  the  muscular  fibres  with  the  nerves, 
364  ;  in  smooth  muscles,  865,  366  ;  in  the  cor- 
nea, 366,  367  ;  in  epithelium,  367,  368  ;  termi- 
nal knobs  of  Krause,  369  ;  tactile  bodies,  869, 
370  ;  Pacinian  or  Vaterian  bodies,  371,  372  ; 
development  of  nerve  fibres,  372,  373  ;  mem- 
branes, 373 ;  pineal  gland  and  brain  sand,  374 ; 


pathological  conditions,   374  ;    methods,  374, 

375. 
Nervus  acusticus,  610  ;   cochlearis,   611 ;   olfac- 

torius,  576  ;  opticus,  596. 
Neumann's  treatment  of  vitreous  body,  270  ;  of 

bones  and   teeth,  293  ;  on  carious  teeth,  298 ; 

on  the  formation  of  colored  blood  corpuscles 

from  the  lymphoid  cells  of  the  bone  medulla, 

307. 

Neuroglia,  357. 
New  formation  of  connective  tissue,  283-286  ; 

varieties  of,   see  the  several  organs  and  tis- 
sues. 

Nicol's  prisms,  52. 
Nitric  acid,  concentrated,  128  ;  with  chlorate  of 

potash,  128,  138  ;  of  20  per  cent.,  314;  dilute, 

Nitzschia  sigmoidea  as  a  test  object,  67. 
Nobert's  test-plate,  35,  70,  71. 
Normal  solutions  (titrition),  146-149. 
Nose-piece,  Brooke's  revolving,  92. 


Objectives,  achromatic,  made  by  Chevalier  and 
Selligne,  12 ;  their  action,  13,  14 ;  aplanatic 
17 ;  designation  of,  15 ;  with  immovable  len 
ses,  15 ;  with  correcting  apparatus,  20,  60 
with  correcting  apparatus  and  for  immersion, 
60  ;  angles  of  aperture,  16,  62,  83 ;  weak,  hi 
combination  with  strong  eye-pieces,  21 ,  23,  83, 
94 ;  strong,  with  weak  eye-pieces,  21-23 ; 
value  of  weak  objectives  in  contradistinction 
to  strong  ones,  93,  99. 

Objectives  of  the  oldest  compound  microscopes, 
8 ;  of  the  modern,  12. 

Odontoblasts,  295. 

Oidiurn  albicans  (thrush)  in  the  oral  cavity,  424  ; 
in  the  stomach,  433. 

Oils,  ethereal,  144. 

Olfactory  cells,  574;  rods,  naked  or  with  cilia, 
574,  575;  connection  with  the  axis  cylinders  of 
the  olfactory  nerve,  576  ;  Schultze's  direc- 
tions for  their  investigation,  517,  578. 

Olfactory  nerve,  pale  fibres  of,  576. 

Olfactory  organ,  572  ;  structure  of  the  ordinary 
mucous  membrane,  572;  catarrhal  process  in 
this,  and  the  formation  thereby  of  mucus  and 
pus  corpuscles,  572,  573;  regio  olfactoria, 
573 ;  olfactory  cells,  574 ;  their  connection 
"With  axis  cylmdei-s  of  the  olfactory  uurve, 
576 ;  Bowman's  and  mucous  glands,  575 ;  me- 
thods of  examination,  576,  57'.;. 

Ollier's  experiments  with  the  periosteum,  308. 

Oral  cavity,  417 ;  condition  of,  423. 

Orthoscopic  eye-piece,  1(5,  94. 

Osmiamide,  163. 

Osmic  acid  (hyperosmic  acid),  135,  162,  163  ; 
acetate  of  potash  for  mounting,  212 ;  its  use 
in  investigations  of  the  retina,  and  Sehultze's 
directions  for  this  purpose,  604. 

Ossicula  auditus,  609. 

Ossification  point  of  bones,  301. 

Osteoblasts,  803,  305. 

Osteogenesis,  300-807. 

Osteogenous  tissue,  805. 

Osteoid  tissue,  305. 

Osteo-malacia,  310. 

Osteo-paresis,  310. 

Osteo-phytes,  309. 

Osteo-sarcoma,  310. 

Otoliths,  610. 

Ovary,  589;  cysts  of,  545. 

Over-corrected  objectives  in  combination  with 
under-corrected  eye-pieces,  18. 

Oviducts,  546. 

Ovum,  540 ;  zona  pellucida,  yolk,  germinal  vesi- 
cle and  germinal  spot,  540. 


624 


IKDEX. 


Owsjannikow  employs  osmiamide,  163. 

Oxalic  acid  in  watery  solution,  133 ;  medium  for 
dissolving  Prussian  blue,  179;  constituent  of 
Thiersch's  tingeing  fluids,  153,  157  ;  action  on 
the  regio  olfactoria,  578  ;  on  the  retina,  598. 

Oxyuris  vermicularis,  ova  of,  in  faeces,  455. 


P. 


Pacinian  bodies,  371. 

Pacini's  preserving  fluids,  213. 

Pancreas,  458,  459. 

Papilio  janira,  scales  of,  as  a  test  object,  63,  64. 

Paraffine,  117. 

Parasites,  animal,  in  faeces,  454;  in  vaginal 
mucus,  548  ;  ova  in  faeces,  455-457 ;  of  the 
skin,  567. 

Parasites,  vegetable,  in  the  oral  cavity,  424 ;  in 
the  stomach,  433  ;  in  the  fasces,  453  ;  of  the 
skin,  565,  566 ;  in  the  urine,  528,  529. 

Parme  soluble,  158. 

Pasteboard  screen,  with  apertures  for  colored 
glasses,  96. 

Pearl  tumors,  265. 

Pencils  for  drawing,  39. 

Penetrating  power  of  the  microscope,  158,  159. 

Pepsin  granules,  427. 

Peptic  gastric  glands,  429. 

Pericardium,  495. 

Peripheral  rays,  refraction  of,  by  a  lens,  9. 

Peritonagum,  495. 

Peyerian  glands,  445. 

Pfliiger  recommends  collodium  for  the  axis 
cylinders,  143,  333 ;  his  investigation  of  the 
salivary  glands,  421 ;  of  the  ovary,  543. 

Photogenic  lamp  for  photographing,  46. 

Photographic  microscopes,  43-46 ;  manipulation, 
44-48. 

Photography,  microscopic,  42 ;  observations  on, 
by  G-erlach,  Beale  and  Moitessier,  43-47  ;  used 
by  Gerlach  for  increasing  the  enlargement,  47, 
48.. 

Picking  preparations,  109. 

Picric  acid  recommended  by  Schwarz  for  tinge- 
ing,  135,  159 ;  by  Ranvier  for  hardening  tis- 
sues, 135. 

Picro-carmine,  92. 

Pigmented  epithelium  of  the  uvea,  589. 

Pipette,  119  ;   for  titrition,  145. 

Pituitary  gland,  374: 

Pityriasis  versicolor,  566. 

Plaque*,  Peyerian,  445. 

Pleura,  495. 

Pleurosigma  angulatum  as  a  test  object,  65. 

Plexus  myentericus  of  Auerbach,  344,  345. 

Polarizer,  52,  53. 

Polarizing  microscope,  52-54. 

Polishing  section  of  bones  and  teeth,  295,  296. 

Porrigo  decalvans,  565 ;   favosa,  566. 

Positive  eye- piece  of  Ramsden,  16. 

Potash  acetate,  138,  212 ;  carbonate,  215 ;  pow- 
der of,  for  examining  pathologically  altered 
tissue  of  brain  and  spinal  cord.  374,  375 ; 
caustic,  136,  137 ;  chlorate,  138 ;  'with  nitric 
acid,  138 ;  potash  solutions  weak  and  strong, 
136. 137  ;  Moleschott's  solutions,  137  ;  Sehult- 
ze's,  137. 

Powell  and  Lealand's  immersion  lenses,  62 ;  mi- 
croscopes, 80. 

Preparations  for  a  cabinet,  204 ;  preserving  in 
weak  alcohol.  204 ;  dry  preparations,  205 ;  of 
Bourgogne  and  others,  205;  in  Canada  bal- 
sam, 205,  208 ;  depriving  the  tissues  of  their 
water,  208 ;  immersion  in  turpentine,  209 ; 
colophony,  210 ;  moist  preparations,  210 ; 
with  glycerine,  210-212,  glycerine  and  gela- 
tine, 211 ;  and  tannin,  211 ;  and  carbolic 
acid,  212 ;  with  gum,  glycerine  and  arsenious 


acid,  212;  acetate  of  potash,  212;  Goadby's 
fluid,  212  ;  Pacinian  fluids,  213  ;  mixtures  of 
the  Berlin  Pathological  Institute,  214 ;  corro- 
sive sublimate,  214,  215  ;  chromic  acid  and 
chromate  of  potash,  2]  5 ;  chlorate  of  potash, 
215  ;  carbonate  of  potash,  215  ;  creosote,  215  ; 
arsenious  acid,  215  ;  methyl  alcohol,  216  ;  and 
creosote,  216  ;  Topping's 'fluid,  216;  Deane's 
216. 

Preparations,  microscopic,  91,  102;  directions 
for  making,  102-119;  mounting  by  simply 
laying  on  the  covering  glass,  216,  217 ;  strips 
of  paper  or  silver  wire  between  slide  and  cover, 
217  ;  with  a  cell,  218 ;  of  gutta  percha,  india- 
rubber,  glass,  218 ;  tinfoil,  cement,  221 ;  size 
and  form  of  the  slides,  225,  226 ;  slides  with 
ledges,  226;  indicator,  225,  226;  cases  for 
preparations,  227 ;  arrangement,  etc.,  227 ; 
revision,  227 ;  collections  and  preparations  for 
sale,  227,  228. 

Preparing  microscope,  109,  110. 

Preserving  fluids,  210-216. 

Price  lists  of  microscope-makers — see  Appendix. 

Primitive  flbrillae  of  the  axis  cylinders  in  the 
nerve  fibres,  335. 

Prisms  for  drawing,  40 ;  in  the  binocular  and 
multocular  microscopes,  49,  50. 

Processus  vermiformis,  449 ;  facility  of  inject- 
ing the  lymphatics  of,  in  the  rabbit,  198,  449. 

Procuring  a  microscope,  71. 

Protoplasma,  102 ;  processes  of  the  central 
ganglion  cells,  349  ;  those  of  the  retina,  606. 

Prussian  blue,  178,  179,  183-185 ;  as  a  medium 
for  impregnations,  recommended  by  Leber, 
166 ;  soluble,  180. 

Psorosperms  of  the  rabbit,  434. 

Pus,  248;  corpuscles  or  cells,  248;  emigration 
from  the  blood-vessels?,  245;  assumed  forma- 
tion within  epithelial  cells  and  connective- 
tissue  corpuscles,  248 ;  amoeboid  transforma- 
tions of  the  cells,  249  ;  their  migrations,  250 ; 
method  of  examining,  250;  acid  and  alkaline 
fermentation  of,  250  ;  method  of  preserving, 
250 ;  corpuscles  in  small  intestines,  434 ;  in 
sputum,  496 ;  in  urine,  527 ;  in  vaginal  mu- 
cus, 548  ;  in  nasal  catarrah,  573  ;  occurrence 
in  corneal  corpuscles,  586. 

Pyramidal  processes  of  the  kidney,  509. 

Pyrogallic  acid,  159. 

Pyroligneous  acid,  use  of,  in  histology,  135. 

Pyrosis,  vomiting  in,  432. 


Rachitis,  bones  in,  307. 

Radial  fibres  of  the  retina,  599. 

Ramsden' s  eye-piece,  16. 

Ranvier  recommends  picric  acid,  135 ;  picro- 
carmine,  160  ;  his  studies  on  connective-tissue 
cells,  276  ;  method  for  examining  the  tendons, 
282. 

Razors,  111;  English,  111  ;  Swiss,  112;  form  of 
the  blade,  111 ;  grinding  and  sharpening,  111. 

Reagents,  chemical,  125  ;  their  use,  125  :  method 
of  application  to  the  microscopic  preparations, 
126  ;  their  more  prolonged  action.  126  ;  accu- 
rate determination  of  their  strength,  126. 

Recklinghausen  recommends  nitrate  of  silver, 
140,  160,  161  ;  moist  chamber,  103  :  discovers 
the  formation  of  red  blood  corpuscles  from  the 
lymphoid  cells  in  the  frog.  233. 

Refraction,  index  of,  of  anis  oil,  acetic  acid, 
glycerine,  Canada  balsam,  turpentine,  ana 
water,  121. 

Refractive  power  of  the  fluid  medium  and  of  the 
object,  120  ;  of  the  fluid  media  changes  the 
microscopic  image,  121. 

Reichert's  connective- tissue    theory,  v277  ;     R. 


INDEX. 


625 


and  Paulsen's  use  of  nitric  acid  for  the  study 
of  the  smooth  muscles,  128,  314. 

Reinicke  recommends  frustula  Saxonica  as  a  test 
object,  65  ;  directions  for  preparing  bone  sec- 
tions, 295. 

Reissneron  the  cochl ear  canal,  611,  612. 

Remak  discovers  the  pale  fibres  of  the  sympa- 
thetic nerve,  337  ;  on  the  development  of  the 
liver.  464. 

Resolving  power  of  the  microscope,  58,  59  ;  its 
relations  to  the  angle  of  aperture,  59.  60. 

Respiratory  organs,  487  :  larynx,  trachea,  and 
bronchi.  487 ;  lungs,  487  ;  methods  of  examina- 
tion, 487;  drying,  488:  hardening,  488 :  in- 
fundibula  and  alveoli,  489  ;  method  of  demon- 
stration, 489  ;  corrosion  method,  489  ;  pulmo- 
nary epithelium,  491  ;  injection  of  the  lym- 
phatics, 492  ;  nerves,  492  :  foetal  lungs,  492  ; 
changes  in  disease.  492  ;  pigmentations  and 
their  signification.  492  ;  anthracosis,  493  ;  pus 
corpuscles,  493  ;  inflammation,  494  ;  tubercu- 
losis, 494  ;  origin  of  the  tubercular  elements, 
494,  495  :  softening,  495  ;  caverns  and  the 
nature  of  their  walls.  495 ;  pleura  (pericar- 
dium and  peritonaeum),  495  ;  sputum,  496  ; 
granule  cells  (inflammatory  globules),  498  ; 
pigment  cells,  498  ;  blood,  498  ;  elastic  fibres, 
499  ;  crystals  of  ammonio-phosphate  of  mag- 
nesia, 499  ;  method  of  examination,  499. 

Richardson,  his  blue  injection  mass.  184  ;  on 
lymphoid  cells.  247. 

RiddelTs  binocular  stereoscopic  microscope,  51, 
85. 

Riff  cells  of  Schultze,  261. 

Rippmann  uses  strong  muriatic  acid  for  the  divi- 
sion of  the  tongue  muscles.  419. 

Robin's  leptothrix  buccalis,  424. 

Rodig's  diatome  test  plate,  65,  note. 

Rods  of  the  retina,  601. 

Rollett  recommends  lirne  and  baryta  water  for 
connective  tissue,  137,  138  ;  on  blood  crystals, 
237  ;  dissolves  the  connective  tissue  of  muscles 
in  hermetically  sealed  tubes  by  slight  warm- 
ing, 320  :  demonstration  of  the  connective- 
tissue  fibrillfe,  and  their  double  arrangement, 
277  ;  on  gastric  glands,  427. 

Ross,  A.,  increases  the  angle  of  aperture  of  ob- 
jectives, 59 ;  microscopes,  80  ;  binocular  stereo- 
scopic microscope,  51. 

Rouget  on  the  termination  of  the  nerves  in  the 
voluntary  muscle?,  362. 

Ruysch's  injections,  170. 

S. 

Sago  spleen,  486. 

Saliva,  425. 

Salivary  corpuscles,  425  ;  of  the  tonsils,  421  ; 
movements  of  their  granules,  425. 

S  ili  vary  glands,  421,  423. 

S  ircina  ventriculi  in  the  contents  of  the  stom- 
ach. 433  :  in  the  urine,  529. 

Sarcine  or  hypoxanthine  in  the  liver,  473  ;  in 
the  urine,  534. 

Sarcolemma — see  Muscles. 

Sarcoma,  284  ;  adenoid  of  the  lacteal  glands, 
551. 

Sarcoptes  hominis,  567  ;  method  of  examining, 
568. 

Sarcous  elements — see  Muscles. 

Saws  for  fine  sections  of!  hard  tissues,  118. 

Scala  media,  611. 

Scall  (porrigo  favosa),  566. 

Schacht  recommends  black  mask  lac  as  a  cement 
for  mounting,  224. 

Schlemm's  canal,  589. 

Schmidt,  C.,  goniometer,  38. 

Schonn  on  the  sarcous  elements  of  muscles,  325. 

Schultze  invents  iodine-serum  as  an  indifferent 

40 


fluid,  124  ;  his  warm  stare,  105  :  compares 
objectives  by  central  illumination  with  No- 
bert's  newest  test  plato,  71 ;  on  stachel  and 
riff  cells,  261  ;  recommends  very  dilute  solu- 
tions of  chromic  acid,  130.  131  :  of  sulphuric 
acid,  127;  oxalic  acid,  182,  133:  caustic  pot- 
ash, 137  ;  osmic  acid,  135,  162,  163  ;  solution 
of  acetate  of  potash  for  mounting,  212  ;  on 
primitive  fibrillas  in  the  axis  cylinder,  335,336  ; 
on  the  complex  structure  of  the  ganglion  cell, 
350  ;  examines  with  Key  the  termination  of 
the  gustatory  nerve  in  the  frog's  tongue,  570  ; 
investigations  of  the  olfactory  mucous  mem- 
brane, 572  ;  follows  the  olfactory  nerve  to  its 
termination,  576  ;  on  the  retina,  596-607  ;  on 
terminations  of  the  auditory  nerve,  610. 

Schulze,  F.  E.,  employs  chloride  of  palladium, 
140,  165  ;  examines  the  becher  cells  of  the  epi- 
thelium, 434. 

Schulze's  reagent,  138. 

Schwarz,  double  tingeing  with  picric  acid  and 
carmine,  159. 

Schweigger-Seidel,  his  mixture  of  glycerine  and 
water,  125;  acid  carmine  mixture,  155;  on 
the  kidneys,  507. 

Scissors.  109. 

Screw  micrometer,  34  ;   in  the  eye-piece,  35. 

Sebaceous  glands  of  the  skin,  410.  562  ;  develop- 
ment in  the  foetus,  564  ;  their  cells,  410  ;  for- 
mation of  these  glands  in  cysts  of  the  ovaries, 
546. 

Section  cutter  of  'Hensen,  112  ;  of  Curtis,  112, 
117. 

Sections  through  hard  objects,  method  of  mak- 
ing, 118,  295,  296  ;  through  very  small  objects, 
117,  118. 

Selenite  plates,  54. 

Semen,  557. 

Seminal  canaliculi.  553  :  stains,  their  investiga- 
tion, 559  ;  filaments,  557  ;  vesicles,  555. 

Sense,  organs  of,  560. 

Serres-fines,  194. 

Shading  microscopic  drawings,  40. 

Sharpey's  fibres  of  bones.  294. 

Shellac  varnish,  with  anilin  blue  or  gamboge, 
for  cementing  Canada  balsam  preparations, 

Silver  impregnation,  160  ;  Recklinghausen's 
method,  160  ;  His'  method,  165  ;  Legros',  161. 

Silver,  nitrate  of,  140,  160. 

Siver  wire  for  supporting  the  covering  glass, 
217. 

Size,  apparent,  of  an  object  determined  by  the 
angle  of  vision,  1. 

Skin,  560  ;  epidermis,  Malpighian  rete  mucosum, 
corium,  sudoriparous  glands,  561  ;  sebaceous 
follicles.  562  ;  blood-vessels  and  lymphatics, 
563  ;  fostal  skin,  564  ;  pathological  changes  of 
the  skin,  564  ;  inflammatory  conditions,  hy- 
pertrophies, elephantiasis,  warts  and  condylo- 
mata,  vascular  na3vi,  &c.,  cysts.  564  ;  athero- 
mata,  comedones,  hordeolum,  565  ;  vegetable 
parasites  :  tricophyton  tonsurans,  microsporon 
Audouini,  565  ;  microsporon  mentagrophytes 
and  furfur,  achorion  Schonleinii,  566  ;  animal 
parasites :  demodex  folliculorum,  sarcoptes 
hominis,  567. 

Slides,  107  :  various  forms.  225,  226. 

Sliding  arrangement  on  objectives  with  correct- 
ing apparatus,  29. 

Soda  solutions,  137  ;  phosphate  of,  138. 

Soemmering's  injections,  170. 

Softening  dried  sections,  134. 

SoHtary  glands,  444. 

Spencer,  Charles  A.,  notice  of,  81. 

Spherical  aberration  of  lenses,  9. 

Spinal  cord.  346. 

Spleen.  477 ;  fresh  organ,  478 ;  hardening 
methods,  478,  479  ;  sections,  479  ;  hardening 


626 


INDEX. 


pathological  organs,  479,  480 ;  mounting.  480  ; 
results  of  investigations,  480  ;  Malpighian  cor- 
puscles, 481  ;  pulp  and  its  canals,  481,  482  ; 
blood-vessels,  482,  483  ;  lymphatics,  484  ;  tra- 
becTilae,  484  ;  nerves,  484  ;  changes  in  disease, 
484  :  in  abdominal  typhus,  485  ;  miliary  tu- 
bercle, 485  :  hemorrhagic  infarction,  485  ;  hy- 
pertrophy, 485  :  pigmentation,  485  ;  amyloid 
degeneration,  486. 

Sputum,  496. 

Stachel  cells  of  Schultze,'261. 

Stage  micrometer,  35. 

Stage  of  the  simple  microscope,  6  ;  of  the  com- 
pound, 23. 

Stage,  warm,  of  Schultze,  105  ;  its  defects,  106. 

Starch  granules  in  saliva,  425  :  in  vomited  mat- 
ters, 431  ;  in  small  intestines,  452  ;  in  faeces, 
452. 

Starch,  reaction  of,  136,  431. 

Stein  on  micro-photography,  46. 

Stereoscopic  microscope,  50. 

Stieda  recommends  creosote  for  rendering  prepa- 
rations transparent,  144  ;  directions  for  pre- 
paring a  cement.  224. 

Sublimate,  140,  212,  215. 

Sudoriparous  glands,  405 :  development,  564  ; 
in  cysts  of  the  ovary,  546. 

Sulphuric  acid,  127,  128  ;  with  iodine  127  ;  ac- 
tion on  the  tissue  of  the  hair,  266,  267  ;  on 
the  nails,  264  ;  on  the  crystalline  lens.  594. 

Supra-renal  glands,  536  ;  structure  of,  536,  537  ; 
nerves,  blood-vessels,  and  lymphatics,  537  ; 
methods  of  investigation,  537,  538. 

Surirella  gemma  as  a  test  object,  65. 

Sympathetic  nerve  fibres,  337  ;  ganglia  of,  340, 
345. 

Syringes  for  injecting,  192  ;  canules,  193,  194  ; 
tying  the  latter  in,  196,  197  :  further  proce- 
dures, 197-201. 


T. 

Tactile  bodies,  369. 

Taenia  booklets  in  the  faeces,  457. 

Taenia  medio-canellata,  ova  of,  in  fasces,  457  ; 
solium,  456,  457. 

Taurine  in  fasces,  454. 

Teeth,  293  ;  decalcifying,  293  ;  chemical  isola- 
tion of  the  dentinal  tubes,  295  ;  sections,  295  ; 
methods,  295,  297;  mounting.  296;  carious 
teeth.  298  :  enamel,  299 ;  sections,  299  ;  isola- 
tion of  the  prisms,  299  ;  pulp.  299  ;  develop- 
ment, 300  ;  formation  of  teeth  in  the  embryo, 
300  ;  in  cysts  of  the  ovaries,  546. 

Teichmann  recommends  chloride  of  silver  for 
injections,  177  ;  employs  the  puncturing 
method  for  injecting  the  lymphatics,  197  ; 
shows  how  to  make  crystals  of  hsemine,  240  ; 
on  blood  crystals,  237. 

Telangiectasia,  564. 

Tendons,  Ranviers  method  of  examining,  282  ; 
relations  with  the  muscle,  320,  321. 

Terminal  knobs,  369  ;  plates  of  the  voluntary 
muscles,  362,  363. 

Test  objects,  62  ;  their  value,  63  ;  enumeration 
of  the  most  important  ones,  63,  69. 

Test  plate  of  Nobert,  35  ;    as  a  test  object,  69, 

Testicles— see  Generative  Organs. 

Thiersch's  injections,   blue,    178  ;     yellow  and 

green,  178,  182,  183  ;    tingeing  methods,  153  ; 

with  indigo-carmine,  157. 
Thrush  (oidium    albicans)   in  the  oral  cavity, 

424  :  in  the  stomach,  433. 
Thymus  gland,  502 ;  concentric  bodies,  265.  504  : 

methods  of    examining.  504  ;    lymphatics  of 

cannot  be  injected,  504. 
Thyroid  gland,  499  ;    relationship  with  other  or- 


gans, 499  ;  blood  and  lymph  passages,  500  ; 
structure,  500  ;  methods,  501  ;  colloid  degen- 
eration and  goitre,  501,  502. 

Tin  chest  for  injections,  192. 

Tin-foil  cells,  221. 

Tingeing  methods,  150  ;  with  red,  150-156  ; 
blue,  156-158  ;  for  injected  preparations,  153; 
lilac  colors.  154  ;  indigo-carmine,  157  ;  parme 
soluble,  158  ;  violet  colors,  hasmatoxylin,  mo- 
lybdanate  of  ammonia,  158  ;  yellow  with  pic- 
ric acid,  159  ;  double  tingeing  with  carmine 
and  picric  acid,  159. 

Tissue  cement  of  the  muscles,  322. 

Titrition  apparatus,  145  ;  method,  145-148  ;  ex- 
amples, 148, 149. 

Toldt's  recommendation  of  benzine,  144 ;  self- 
injection  of  the  lymphatic  glands,  398. 

Tolles,  R.  B.,  notice  of,  84. 

Tongue,  418  ;  division  of  the  muscular  filaments, 
419  ;  connection  with  connective-tissue  cor- 
puscles, 419  ;  nerves,  419,  569  ;  their  termina- 
tions examined  by  Schultze  and  Key,  570  ; 
modified  by  Engelmann.  571. 

Tonsils,  420. 

Topping's  fluids,  216. 

Trachoma  glands  of  the  conjunctiva,  580;  their 
lymphatics,  580  ;  injection,  581. 

Transparent,  reagents  for  rendering  tissues, 
121. 

Trichina  spiralis  in  muscles,  329;  examination 
of  trichinised  muscles,  330  ;  trichina  in  the 
faeces,  455  ;  microscopes  for  examining,  330, 
note. 

Trichomonas  vaginalis,  548. 

Tricophyton  tonsxirans,  565. 

Tricocephalus  dispar,  ova  of,  in  fasces,  455. 

Tube  of  the  microscope,  23. 

Tubercles,  284. 

Turpentine,  oil  of,  its  property  of  rendering  tis- 
sues transparent,  121  ;  index  of  refraction, 
121  ;  medium  for  dissolving  Canada  balsam, 
206  ;  removal  of  the  preparation  from  alcohol 
to  oil  of  turpentine,  and  from  this  to  Canada 
balsam,  209. 

Tympani  membrana,  609. 

Tyrosine  in  the  liver,  471,  472  ;  in  urine,  534, 
535. 


U. 


Ulcers,  249. 

Urate  of  ammonia,  533  ;   of  soda,  529. 

Urea,  oxalate  and  nitrate  of,  535. 

Ureter,  526. 

Urethra,  556. 

Uric  acid,  529  ;   infarctions,  525  ;   salts,  529. 

Urinary  organs,  505 ;  kidneys  with  medulla  and 
cortex,  505  ;  earlier  views,  505  ;  Henle's  newer 
observations,  506;  later  investigations,  507; 
method  of  examining,  507,  5U8 ;  hardening,  508: 
longitudinal  and  transverse  sections,  509,  510  ; 
chemical  isolation,  511,  512;  injection  of  the 
uriniferous  canals,  515-517 ;  diagram  of  the 
course  of  the  canalicules,  517  ;  self -injection, 
517 ;  arrangement  of  the  vessels,  517,  518 ; 
vasa  recta,  519;  double  injection.  520 ;  selec- 
tion of  material,  520  :  lymphatics,  521  ;  patho- 
logical changes,  521 ;  importance  of  the 
gland  cells  and  frame-work,  521 ;  hypertrophy, 
tubercle,  fatty  pigment  and  amyloid  degene- 
ration, 522,  523  ;  Bright's  disease,  524,  525 ; 
precipitates  in  the  uriniferous  canals,  525.  526 ; 
uric  acid  and  lime  infarctions,  525,  526  :  calices 
and  pelvis  of  the  kidney,  ureters  and  bladder, 
526. 

Urine,  526;  fresh,  normal,  526;  constituents. 
526  ;  abnormal  constituents  in  disease :  epithe- 
lium, mucous  and  pus  cells,  blood-corpuscles, 


INDEX. 


627 


527 ;  fibrin  exudation  cylinders,  527  ;  saroina 
ventriculi,  529 ;  sediment,  529.  530 ;  uric  acid 
of  various  crystalline  forms,  529,  530 ;  urate 
of  soda,  529 ;  oxalate  of  lime,  532 ;  fermen- 
tative fungi,  532,  533;  ammonio-phosphate  of 
magnesia.  533 :  urate  of  ammonia,  533 ;  for- 
mation of  mould  and  vibrionae  in  alkaline 
urine.  533,  534;  crystals  of  cystine,  534: 
leucine  and  tyrosine,  535 ;  urea  combined 
with  nitric  and  oxalic  acids,  535 ;  sarcine  and 
xanthine,  535  :  method  of  examining  the  pre- 
cipitates, 535,  536. 

Urimferous  canalicules,  505,  506;  loop-shaped, 
506,  507,  513-515,  517. 

Uterine  glands,  546  ;   cancer,  547  ;   polypi,  547. 

Uterus.  546  ;   fibroid  tumors  of,  547. 

Uroa,  589. 


V. 

Vagina,  547  ;   mucus  of,  548. 

Valentine,  his  double  knife.  Ill ;  his  investiga- 
tion of  the  ciliary  movement,  260 ;  examines 
the  behavior  of  muscles  in  polarized  light,  327; 
the  nerves,  327. 

Vas  deferens.  553. 

Vaterian  bodies— see  Pacinian  Bodies. 

Veins— see  Blood- Vessels. 

Vessels,  new  formation  of,  391. 

Vestibule  of  the  fish,  sacculi  of  the,  610. 

Vibriones,  formation  of  in  alkaline  urine,  533. 

Vinegar,  134  ;  boiling  the  kidney  in,  recommen- 
ded by  Billroth,  511. 

Virchow's  discovery  of  haBmatoidine,  241 ;  direc- 
tions for  isolating  bone  cells,  293  ;  tor  repro- 
ducing the  ciliary  movements,  259. 

Visual  apparatus,  579  ;  eye-lids,  Meibomian  and 
lachrymal  glands,  conjunctiva,  coil-shaped 
glands,  terminal  knobs,  579;  blood-vessels, 
lymphatics  with  trachoma  glands,  580  ;  eye- 
ball, 581 ;  method  of  injecting  and  examining, 
581,  582  :  cornea,  583  ;  pathological  changes, 
588;  sclerotic,  589;  uvea,  589;  pigment 
epithelium,  589  ;  choroid  with  its  layers,  590  ; 
chorio-capillaris,  591 ;  senile  metamorphoses 
of  the  elastic  lamellae,  591 ;  ciliary  muscle, 
591;  ciliary  body,  592;  iris,  591;  vitreous 
body,  269,  592 ;  lens,  592-595 ;  its  metamor- 
phoses, 594 ;  membrana  hyaloidea,  595 ;  zonu- 


la  zinii,  595 ;  retina,'595  ;  its  structure,  596  • 
various  layers,  596 ;  connective-tissue  frame- 
work, 598 :  rods  and  cones,  600 ;  intergranu- 
lar  layer,  603 ;  membrana  limitans,  602 :  granu- 
lar layer.  603 ;  layer  of  ganglion  cells',  603 ; 
vessels,  607:  pathological  conditions,  608- 
foetal  eyes,  608. 
Vitreous  body  of  the  eye,  269,  270,  592. 


W. 


Wagner,  E.,  on  the  liver,  464,  469 ;   on  fat  em- 

bolia  of  the  capillaries,  391. 
Waldeyer's  axillary  nerve  fibrillae,  335 
Wales,  Wm..  notice  of,  84. 
Warming  the  gelatine  masses  for  injections,  172, 

Warts,  564;  dry,  265. 

Watch-glasses,  107. 

Water,  124 ;  index  of  refraction,  121 ;  is  not  an 
indifferent  fluid,  121. 

Water-batli  for  gelatine  injections,  172. 

Water-colors  for  microscopic  drawings,  40. 

Wax  as  an  injection  mass,  170. 

Waxy  liver,  475. 

Welcker's  method  of  distinguishing  between 
elevated  and  depressed  surfaces,  99. 

Wenham's  arrangement  of  the  binocular  stereo- 
scopic microscope,  51. 

Wittich's  method  of  isolating  striated  muscles, 
320. 

Work-room  of  the  microscopist,  87. 

Work-table  of  the  microscopist,  96. 


X. 


Xanthine  in  the  liver,  473  ;  in  urine,  535. 


Zeiss'  microscope  for  dissections,  110. 

Zenker  on  the  muscles  in  typhus,  329. 

Zentmayer,  J.,  notice  of,  84. 

Ziegler's  cement,  223. 

Zinc  white,  as  an  injection  mass,  176. 

Zonula  zinnii,  595. 

Zoosperms— see  Seminal  Filaments. 


PRICE-LISTS  OF  MICROSCOPE  FIRMS. 


No.  I. — Price-List  of  the  Achromatic  Microscopes  of  E.  HARTNACK  &  Co., 
Successors  to  Or.  OBEKHAUSER  &  Co.,  Paris  (21  Place  Dauphine)  and 
Potsdam  (1870). 

Price  in  Franc*. 

Remarks. — All  Microscopes  are  contained  in  a  mahogany  case,  furnished  with  a  lock  and  key. 

2.  The  models,  Nos.  1,  2,  3  and  3A  are  furnished  with  lens  systems  of  older  construction.     The 

remainder  have  new  lens  systems,  with  large  angles  of  aperture. 

3.  From  its  arrangement,  the  polarizing  apparatus  may  be  advantageously  employed  on  the  models 

from  4  to  8. 

4.  From  the  following  tables  other  systems  and  eye-pieces,  which  are  required  in  the  place  of  the 

customary  ones,  as,  indeed,  any  desired  outfit,  may  be  readily  reckoned. 

A*    Prices*  of  the  Individual  Lens  Systems,  and  of  -the  other 
Apparatuses. 

LENS   SYSTEMS   OF    OLDER   CONSTRUCTIONS.      MAGNIFYING   POWER  WITH  THE 

EYE-PIECES. 


System. 

Eye-piece 
No.  1. 

No.  2. 

No.  3. 

No.  4. 

No.  5. 

No.  6. 

Price. 

No.  1  

12 

15 

25 



12 

2.  .  . 

20 

30 

40 

20 

3. 

30 

40 

50 

20 

4  

40 

50 

65 

100 

20 

75 

100 

150 

200 

30 

6  

110 

150 

220 

300 

35 

150 

220 

300 

450 

35 

8 

250 

300 

400 

600 

800 

40 

9  

360 

430 

550 

850 

1000 



60 

NEW  LENS  SYSTEMS  WITH  LARGE  ANGLES  OF  APERTURE. 


System. 

Eye- 
piece. 
No.  1. 

No.  2. 

No.  3. 

No.  4. 

No.  5. 

No.  6. 

Price. 

Equivalent 
focus  in 
inches. 

No.  1. 

15 
25 

50 
60 
100 
150 
200 
250 
350 

20 
32 
60 
70 
125 
180 
240 
300 
440 

25 
45 

80 
90 
160 
240 
300 
400 
550 

120 
140 
240 
350 
450 
600 
860 

600~ 
800 
1100 

750~ 
1000 
1400 

15 
20 
25 

30 
35 
35 
40 
50 
75 

2 
1 

1 

% 

& 

1-9 
1-11 

2 

3 

4  .. 

5 

6  

7.. 

8 

9  

NEW  SYSTEMS  WITH  IMMERSION  AND  CORRECTION. 


System. 

Eye. 
piece. 
No.  1. 

No.  2. 

No.  3. 

No.  4. 

No.  5. 

No.  6. 

Price. 

Equivalent 
focus  in 
inches. 

No.  9  

410 
520 
600 
710 
820 
930 
1040 
1200 
1400 
1560 

480 
600 
690 
820 
950 
1080 
1200 
1400 
1600 
1800 

630 
750 
boO 
1010 
1170 
1340 
1500 
1750 
2000 
2250 

950 
1100 
1250 
1490 
1730 
2000 
2200 
2570 
2940 
3300 

1300 
1500 
1750 
2060 
2370 
2680 
3000 
3500 
4000 
4500 

1500 
1800 
2500 
2800 
3100 
3350 
3600 
4200 
4800 
5400 

150 
200 
250 
300 
350 
400 
450 
500 
500 
500 

1-12 
1-lb 
1-18 
1-21 
1-25 
1-28 
1-33 
1-40 
1-45 
1-50 

1C.. 

11 

12.. 

13  . 

14  

15.. 

16  

17.. 

18  

630  PKICE-LISTS    OF    MICROSCOPE    FIRMS. 

Plain  eye- piece 10  fr 

Holosteric  eye-piece 15  fr. 

Eye-piece  with  adj  listing  screw 25  fr. 

Micrometer  eye-piece 25  fr. 

-  Binocular  stereoscopic  eye-piece 180  fr. 

Movable  stage 40  f r . 

Simple  compressorium 20  fr. 

New  compressorium 25  fr. 

Stage  micrometer  mounted  in  brass,  the  millimetre  divided  into  100,  500  and  1000  parts 20  fr. 

New  movable  micrometer  (gives  with  great  accuracy  0.0001  millimetre) 50  fr. 

Polarizing  apparatus 50  fr. 

Improved  patent  polarizing  apparatus,  with  a  polarizing  eye-piece,  a  prism  with  a  large  field 
of  vision,  and  a  graduated  circle 60  fr. 

Goniometer (50  fr. 

Universal  goniometer , 150  fr. 

Dujardin's  illuminating  apparatus  (improved  construction) 50  fr. 

Camera  lucida  of  Oberhauser  ;  also  serving  for  the  conversion  of  the  vertical  into  the  hori- 
zontal microscope 50  fr. 

Camera  lucida  of  Milne-Edwards  and  Doyere 35  fr. 

Briicke's  loup  (improved  construction) 20  fr. 

Stand  for  this  loup 30  fr. 

Loupe 5-15  fr. 

Lamp  for  microscopic  examinations,  with  a  large  illuminating  lens  for  obtaining  parallel  rays 
of  light 35  fr. 

Object  slides,  first  quality,  per  dozen 2  fr . 

Object  slides,  second  quality,  per  dozen 1  f  r. 

Fine  covering  glasses,  per  dozen,  1  f  r. ;  per  hundred 6  f  r. 

B.    Prices  of  the  several  Microscopes. 

No.  I. — Small  microscope  (d'hospice),  with  a  lens  system  Xo.  7,  and  an  eye-piece  No.  3  ;  mag- 
nifying power,  '600 ;  with  a  dozen  slides  and  thin  covers,  brass  forceps,  scalpel  and  pre- 
paring needles 65  fr. 

No.  II.  Achromatic  microscope  (with  a  wider  stage),  furnished  with  the  lens  systems  4  and 
7,  eye-pieces  2  and  3,  and  an  illuminating  lens  for  opaque  bodies.  Magnifying  po\\  tr  from 
50,  65,  220  to  300  diameters,  micrometer-screw  on  the  stage,  rotary  diaphragm 115  fr. 

The  same  instrument,  with  the  addition  of  lens  system  8,  and  eye-piece  4 ,  magnifying  power 
from  50-600 165  fr. 

No.  II.  A. — Achromatic  ^microscope,  with  firm  stage ;  micrometer  screw  on  the  stem  ;  mirror 
freely  movable  for  oblique  illumination ;  optical  apparatus  as  in  II 120  fr. 

To  obtain  a  magnifying  power  up  to  600 170  fr. 

No.  III. — Achromatic  microscope,  small  drum  stand,  with  a  firm,  large  stage,  rotary  dia- 
phragm, and  the  same  optical  apparatus 140  fr. 

To  obtain  a  magnifying  power  up  to  600 190  fr. 

No.  III.  Achromatic  microscope ;  stand,  in  its  upper  part,  similar  to  the  previous  one  ;  but 
having  a  horse-shoe  foot ;  freely  movable  mirror  for  oblique  illumination  ;  optical  appara- 
tus the  same 140  fr. 

To  obtain  a  magnifying  power  up  to  600 190  f  r. 

No.  1II.A. — Achromatic  microscope,  similar  to  the  previous  one  ;  the  stem  is,  however,  pro- 
vided with  a  joint  for  obtaining  an  oblique  position  ;  optical  apparatus  the  same 155  fr. 

To  obtain  a  magnifying  power  up  to  600 205  fr. 

No.  IV. — Achromatic  micioscope  vith  rotary  stage,  and  a  black  glass  plate  on  the  same  ;  cylin- 
drical diaphragms ;  lens  systems  4  and  7,  new  construction,  and  eve-pieces  2  and  3  ; 
magnifying  power,  70,  90,  220,  300. .  . , * 300  fr. 

To  obtain  a  magnifying  power  of  650 360  fr. 

No.  V. — Large  achromatic  microscope  ;  foot  and  stage  the  same,  only  larger  and  more  firm  ; 
optical  apparatus  the  same  as  with  No.  IV 340  fr. 

To  obtain  a  magnifying  power  of  650 400  f  r. 

No.  VI.  Achromatic  dissecting  microscope,  with  long  focal  distarce  and  inversion  of  the 
image ;  magnifying  power  (without  changing  the  lenses  or  eye-pieces)  from  10-100.  Rotary 
stage  with  glass  plate 250  fr. 

No.  VII.  New,  large  patent  achromatic  microscope,  the  mechanical  and  optical  construction 
of  which  differ  essentially  from  the  older  large  ^Oberhauser's)  stand.  It  consists  of  5  lens, 
systems  2,  4,  5,  7,  and  the  immersion  system  9,  and  5  eye- pieces  (one  of  which  has  a 
micrometer)  ;  magnifying  power  from  25-1,300  (each  succeeding  enlargement  twice  as 
great  as  the  previous  one).  Coarse  movement  by  an  adjusting  screw,  the  fine  one  by  a 
micrometer  screw.  Large  illuminating  lens  for  opaque  objects  ;  all  the  necessary  acces- 
sory apparatus 750  fr. 

The  same  stand  with  a  joint  for  inclining 800  fr. 


PRICE-LISTS    OF    MICROSCOPE    FIRMS.  631 

No.  VILA.  Achromatic  -microscope  of  the  same  construction,  but  somewhat  smaller  and 
without  the  adjusting  screw  for  the  coarse  movement ;  optical  arrangement  the  same.  .650  fr. 

The  same  stand  with  a  joint  for  inclining 680  f r. 

No.  VIII.  New  small  stand,  the  arrangement  of  which,  with  the  exception  of  the  rotation 
of  the  stage,  presents  the  same  advantages  as  the  microscope  No.  VII. ;  with  the  lens, 
systems  4  7,  8,  and  eye-pieces  2,  3,  4  ;  magnifying  from  50-650  times 275  fr. 

The  same  with  the  lens  systems  4  and  7,  as  well  as  the  immersion  system  9,  and  3  eye-pieces, 
one  of  which  is  provided  with  a  micrometer ;  magnifying  from  50-1,000  times 390  fr. 

With  a  joint  for  inclining 405  fr. 

No.  2.— NACHET  &  SON,  17  Rue  Saint  Severin,  Paris  (1872). 

Price  in  Francs. 

1.  Microscope,  large  model,  improved,  complete  and  binocular,  suspended  on  the  axis  in  such 

a  manner  that  it  may  be  inclined  and  remain  fixed  in  any  position  between  the  horizontal 
and  vertical.  Coarse  adjustment  by  rack  work ;  two  movements  for  fine  adjustment,  one 
acting  on  the  column  supporting  the  body,  the  other  very  delicate  and  belonging  especially 
to  the  tube  carrying  the  objectives,  and  so  disposed  as  to  establish  a  constant  elasticity  for 
the  protection  of  the  objectives  in  case  of  contact  with  the  preparation.  The  stage  is 
rotable  and  is  furnished  with  a  double  plate  and  so  arranged  that  the  objects  may  be  moved 
without  touching  them.  The  stage  is  furnished  with  a  glass  plate  to  resist  the  destructive 
effects  of  reagents.  Illumination  by  a  double  mirror  movable  in  all  directions.  A  sliding 
arrangement,  placed  between  the  mirror  and  stage,  permits  of  the  removal  of  the 
diaphragms  and  of  focussing  the  condensers  with  the  greatest  precision.  Micrometric  ap- 
paratus for  introducing  the  micrometer  into  the  eye-pieces  without  deranging  them,  and 
for  accurately  adjusting  it  to  the  focus  of  the  eye,  and  for  placing  it  in  all  parts  of  the  field 
of  vision.  Eight  objectives  with  correcting  apparatus,  from  No.  0  to  No.  7.  Magnifying 
from  30-1,4,0  diameters;  four  eye-pieces,  binocular  apparatus,  goniometer,  camera  lucida, 
polarizing  apparatus  with  selenite  plates,  condenser,  eye-piece  and  stage  micrometers. 
Condensing  lens  on  a  stand.  Accessories  for  preparing.  Strong  mahogany  case  with 
brass  corners,  lined  with  velvet ;  objectives  in  a  separate  case 1,400  fr. 

2.  Microscope,  large  model,  mounted  like  No.  1.     Rotary  stage  with  a  black  glass  plate  for  use 

with  acids.  Rock-work  for  coarse  adjustment,  slider  for  diaphragms  and  condenser, 
double  mirror,  3  eye-pieces,  6  objectives,  Nos.  0,  1,  2,  3,  5,  7,  for  immersion  and  correc- 
tion, magnifying  from  30-1,400  diameters.  Camera  lucida,  eye-piece  and  stage  micrometers, 
condensing  lens,  accessories  for  dissections,  etc.  Mahogany  case,  brass  corners,  etc 680  fr. 

3.  Vertical,  large  model,  rotary  stage,  coarse  and  tine  adjustment,  arrangement  for  introducing 

the  diaphragms  and  condenser  without  deranging  the  object;  eye-piece  and  stage  microm- 
eter ;  5  objectives,  Nos.  1,  2,  3,  5,  7,  immersion  and  correction,  magnifying  from  30- 
1,400  diameters.  3  eye-pieces,  camera  lucida,  condensing  lens,  accessories  for  dissecting, 
etc.  Mahogany  case,  etc 550  fr. 

4.  "  Microscope  ft  disposition  particuli^re^  to  reduce  the  height  as  much  as  possible,  model  of 

Prof.  H.  de  Lacaze-Duthiers — same  objectives  as  in  the  model  No.  3 650  fr. 

5.  Microscope,  medium  model  for  inclining.  Coarse  and  fine  adjustment,  rotary  stage  and  glass 

plate,  double  mirror,  apparatus  for  adjusting  diaphragms  beneath  the  object,  etc.,  5  ob- 
jectives, Nos.  1,  2,  3,  5,  7,  immersion  and  correction,  magnifying,  with  3  eye-pieces,  from 
30-1,400  diameters,  condensing  lens,  accessories,  eye-piece  micrometer,  etc.  Mahogany 
case 500  fr. 

6.  Vertical,  medium  model,  similar  to  No.  3 ;  rotary  stage,  black  glass  plate,  5  objectives,  Nos. 

1,  2,  3,  5,  7,  immersion  and  correction,  3  eye-pieces,  eye-piece  micrometer,  condensing 
lens,  accessories.  Mahogany  case  450  fr. 

7.  New  model  for  inclining.     Immovable  stage,  block  glass  plate,  coarse  and  fine  adjustment, 

diaphragm  arrangement  as  in  medium  models ;  condensing  lens,  3  eye-pieces,  4  objectives, 
Nos.  1,  3,  5,  7,  immersion  and  correction,  magnifying  from  25-1, 400  diameters,  accessories. 

Mahogany  case 430  fr. 

S.  Same  microscope  with  3  objectives,  Nos.  1,  3,  5  ;  magnifying  30-700  diameters 280  fr. 

9.  Small  model  for  inclining ;  mirror  freely  movable,  movable  diaphragm,  coarse  and  fine  ad- 

justment, draw  tube,  2  objectives,  Nos.  1,  3;  2  eye-pieces  ;  magnifying  from  30-500  diam- 
eters ;  condensing  lens,  accessories.  Mahogany  case 150  fr. 

The  same  with  3  objectives,  Nos.  1,  3,  5,  and  3  eye-pieces ;  magnifying  from  30-700  diam- 
eters  200  fr. 

10.  Small  model,  vertical.     Mirror  freely  movable ;  2  objectives,  Nos.  1,  3 ;   2  eye-pieces,  con- 
densing lens,  accessories.   Mahogany  case 125  f  r. 

With  3  objectives,  Nos.  1,  3,  5,  and  3  eye-pieces ;    magnifying  from  30-700  diameters 175  fr. 

11.  More  simple  microscope.     Cast  iron  base,  1  eye-piece,  1  objective,  No.  3 ;  maximum  380 
diameters,  accessories.      Mahogany  case 80  fr. 

The  same  with  objective  replaced  by  No.  5,  magnifying  500  diameters 90  fr. 

12.  Large  model,  binocular  microscope.     Constructed  in  such  a  manner  as  that  the  prismatic 
apparatus  gives  at  pleasure  stereoscopic  or  pseudoscopic  images.      The  eye-pieces  may  be 
approximated  or  separated  according  to  the  distance  between  the  eyes  of  the  observer  ; 


632 


PKICE-LISTS    OF    MICKO SCOPE    FIRMS. 


coarse  and  fine  adjustment,  may  be  inclined  horizontally,  3  objectives,  Nos.  0,  1,  3  ;   mov- 
able stage,  condensing  lens.      Mahogany  case 500  fr. 

13.  Small  model,  binocular,  for  inclining ;  coarse  and  fine  adjustment,  3  objectives,  Nos.  0, 1,  3 ; 

2  eye-pieces,  condensing  lens  ;  case 350  fr. 

14.  Binocular  apparatus,  applicable  to  all  microscopes,  with  arrangement  for  adjusting  to  dis- 
tance between  the  eyes  ;   2  eye-pieces,  no  objectives 150  f r. 

15.  Binocular,  stereoscopic  and  pseudoscopic  apparatus,  applicable  to  all  microscopes 175  fr. 

16.  Microscope  for  two  persons  to  observe,  simultaneously,  the  same  object.  Objectives,  Nos.  0, 

1,  3  ;  condensing  lens,  accessories,  etc. ;  case 300  f  r. 

17.  Double  body  to  apply  to  ordinary  instruments ;  2  eye-pieces,  no  objectives 80  fr. 

18.  Microscope  for  three  persons  to  observe,  simultaneously ;    coarse  and  fine  adjustment ;  each 
observer  may  adjust  the  focus  separately  ;   3  objectives,  Nos.  0,  1,  3  ;  case 400  fr  . 

19.  New  large  model,  inverted,  with  a  silvered  mirror  at  the  crossing  of  the  rays.   In  this  mi- 
croscope the  distance  between  the  objective  and  the  eye-piece  may  be  increased  to  90 
centimetres  or  1  metre  without  inconvenience.    This  combination  requires  a  very  delicate 
construction  of  the  mounting.      The  strongest  objectives  may  be  used  in  this  form  of 
instrument,  the  loss  of  light  produced  by  the  silvered  mirror  (Foucault:s  method)  being 
insignificant.    Achromatic  condenser,  mirrors,  2  eye-pieces,  no  objectives 800  fr. 

20.  Inverted  microscope  for  chemical  studies.     The  objectives  being  placed  under  the  object, 
there  is  no  liability  of  clear  vision  being  impaired  by  the  accumulation  of  vapors.      The 
stage  is  gilded ;  4  objectives,  Nos.  0,  1,  3,  5  ;  1  movable  eye-piece,  accessories,  alcohol  lamp 

on  an  articulated  support,  excavated  slips  of  glass,  thin  covers.     Mahogany  case 350  fr. 

21.  New  in  verted*  microscope  for  the  study  of  anatomical  elements  in  gases  at  a  steady  tem- 
perature, with  numerous  accessories ;   3  objectives,  Nos.  1,  3,  5  ;  2  eye- pieces  ;   case  —  500  fr. 

22.  Pocket  microscope.    The  instrument  is  90  millimetres  long  by  50  millimetres  broad,  can  be 
used  with  high  powers ;  objectives,  Nos.  1,  3,  5,  are  usually  added  ;  one  eye-piece,  slides 
and  covers,  all  in  a  compact  leather  case 200  f  r. 

23.  New  portable  microscope,  larger  than  the  preceding  one,  enclosed  in  a  case  14  centimetres 
long  by  8  broad ;  movable  mirror ;  all  objectives  may  be  used ;  with  3  objectives,  Nos.  1,  3,  5, 
and  1  eye-piece 180  f  r. 

24.  Dissecting  microscope,  model  of  Dr.  Cosson.     This  instrument  has  on  one  side  an  arm  for 
carrying  the  doublets  for  dissections,  and  on  the  other  a  column  with  a  horizontal  support 
for  the  body  of  the  microscope.      It  may  be  used  either  as  a  simple  or  compound  micro- 
scope at  pleasure.  Coarse  adjustment  for  the  doublets,  fine  for  the  compound  microscope. 
2  objectives,   Nos.  1  and  3  ;    eye-piece  ;  3  doublets  of  varying  powers  ;  condensing  lens ; 
case 140  f  r . 

25.  Stage  of  this  microscope  alone,  as  a  simple  microscope  with  3  doublets,   and  base,  with 
articulations  for  supporting  the  doublets  ;  accessories  ;  case 50  fr. 

26.  Dissecting  microscope  for  laboratories,  model  of  Prof.  Ch.  Robin.     May  be  used  with  glass 
dishes  or  plates  of    cork  on  which  opaque   objects  are  fixed.      It  gives  erect  images  and 
magnifies  from  8-70  diameters 120  fr. 

A  stage  with  a  mirror  may  be  added  for  dissecting  very  small  objects 20  fr. 

27.  Hand  microscope  for  demonstrations.    The  instrument  may  be  placed  on  a  stand  till  the 
object  is  permanently  adjusted,  and  then  passed  among  the  audience.     All  kinds  of  illu- 
mination may  be  used  ;  coarse  and  fine  movement ;  without  objective 80  fr. 

28.  Microscope  on  a  support  for  aquaria,  without  objective 120  fr. 

29.  Photographic  microscope,  with  accessories  and  a  series  of  objectives 300  fr. 

30.  Dark  chamber,  etc 80  fr. 

Moitessier's  photographic  frames 45  fr. 

OBJECTIVES. 

MOUNTED   IMMOVABLE. 

No.  0 15fr.No.4 35  fr. 

1 20fr.          5 40fr. 

2 25fr.          6 50fr. 

3 30fr.          7 80fr. 

OBJECTIVES  WITH  CORRECTION. 

No.3...  ..  50fr.lNo.  6  ..  100  fr. 

4 60  fr.          7 125  fr. 

5 75fr.l 

IMMERSION    OBJECTIVES. 

MOUNTED  IMMOVABLE. 

No.  6 70  fr.  |  No.  7 100  fr. 


PEICE-LISTS    OF    MICROSCOPE    FIRMS. 


633 


IMMERSION  OBJECTIVES  WITH  CORRECTING  APPARATUS. 


No.  6 

7... 


8 200  fr. 

9...  ...250fr. 


.120  fr.  No.  10 300  fr. 

.150  fr.         11 350  fr. 

12...  ...400fr. 


LINEAR     MAGNIFYING     POWER     OBTAINED     BY     THE     COMBINATION     OP    THE 
OBJECTIVES  WITH  THE  EYE-PIECES. 

ORDINABY  OBJECTIVES. 


0 


2 


I  1 30  80  180  260  300  350 

Eye-pieces  1  2 40  100  260  380  420  480 

(3 60  140  350  500  590  680 

Corresponding  focus  in  inches 2  1  1-2  1-4  1-5  1-8 

Angle  of  aperture— degrees 10  15  40  90  90  130 

IMMEBSION   AND  CORRECTION   OBJECTIVES. 

|      6          7          8          9         10         11         12 

f   1 460       580       775       900      1150      1320      1700 

Fvpniw«J    2 i  6CO        90°      110°      180°      156°      180°      240° 

ss]    3 '900     1400      1600      2000      2200      2680     3260 

[4 1200      1750      2000      2500      2750      3150     4500 

Corresponding  focus  in  inches I    1-10      1-14      1-15      1-20      1-30      1-40      1-50 

Angle  of  aperture— degrees I  140       160       175       175       175       175       175 

31.  Simple  microscope  for  dissections,  with  doublets,  rack-work  for  coarse  adjustment,  two 
wings  at  the  sides  of  the   stage  for  the  support  of  the  hands  in  fine  dissections,  with  two 
doublets  and  case 60  fr. 

32.  Binocular  microscope  for  dissections,  magnifying  10-150  diameters 150  fr. 

33.  Loupestand,   movement  for  adjusting  the  focus,  new  system  of  camera  lucida;  and  2 
doublets 80  fr. 

34.  Porte-loup,  large  model  of  Lacaze-Duthiers,  with  illuminating  lens  and  multiple  articula- 
tions for  supporting  the  doublets  under  the  rays  of  light ;  2  doublets ;  mounted  on  a  thick 
board  which  can  contain  all  the  apparatus,  thus  rendering  it  very  portable 80  fr. 

35.  Artictalated  stand  with  rack-work,  without  loupe . : 15  fr. 

36.  The  same  without  the  rack-work  8  fr. 

37.  Briickfe's  loupe *. 15  fr. 

38.  Doublets  for  dissections,   focal  distance,  20-5  mm.  each 6  fr. 

39.  do.  5-2  mm 10  fr. 

40.  Stage  micrometer,  mounted  in  copper,  the  millimetre  in  100  Ibs 10  fr. 

41.  do.  millimetre  in  500  Ibs 20  fr. 

42.  do.  "  "lOOOlbs 30  fr. 

43.  Camera  lucida 25  fr.1 

44.  do.  ordinary,  old  form 18  fr. 

45.  Erecting  prism,  may  be  applied  to  all  instruments 25  fr. 

46.  do.  perfected,  combined  with  an  eye-piece  to  give  a  larger  field 35  fr. 

47.  Revolving  object-bearer 25  fr. 

48.  Condenser,  direct 25  fr. 

49.  do.        oblique 15  fr. 

50.  Amici's  illuminating  prism,  mounted  on  a  separate  base,  with  articulations 25  fr. 

51.  Black  ground  illumination 15  fr. 

52.  Polarizing  apparatus,  perfected,  2  Nicols',  placed  one  beneath  the  object,  the  other  over  the 

eye-piece 40  fr. 

53.  Goniometer 30  fr. 

54.  Section-cutter 60  fr. 

55.  do.  simplified 35  fr. 


634  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

56.  Microtome  for  holding  the  objects  to  make  sections  by  hand,  with  glass  plate,  model  of 

Dr.  Hayem  ........................................................................  18  fr. 

57.  Compressor  ..........................................................................  30  fr. 

58.  Eye-pieces,  each  .....................................................................  10  fr. 

do.         "        very  strong,  achromatic  .............................................  20  fr. 

59.  Eye-piece  micrometer  ................................................................  15  fr. 

No.  3.  —  Price-List  of  Microscopes  of  G-.  S.  MERZ,  formerly  UTZSCIINEIDER  & 
FRAUNHOFER,  in  Munich  (1869). 

Price  in  Guldens  and  Thalers. 
A.    Complete  Microscopes. 

Microscope  No.  1,  with  stand  No.  1,  vertical,  firm  stand,  horizontal  rotary  stage  (English 
form),  coarse  and  fine  movement  on  the  tube,  double  mirror  and  loup  for  opaque  objects. 
The  instrument  is  provided  with  6  objectives,  ^  ^  ^  ^  1-^  ^"^  and  6  eye-pieces, 
1,  1^",  2.  2>£,  3,  4  ;  affords  a  magnifying  power  of  60-1.920  diameters.  It  has  a  screw  mi- 
crometer with  which  even  0.0001  of  a  Paris  line  may  be  measured,  a  polarizing  apparatus, 
a  drawing  prism  and  a  compressorium.  The  whole  in  an  elegant  case.  .Price,  4^0  fl.=240  thlr. 

Microscope  No.  2,  with  stand  No.  1  ;  3  objectives,  1?  J^  1^"^  and  4  eye-pieces,  60-1,440 
diameters  ;  glass  micrometer  included  ...............................  Price,  175  fl.  =  100  thlr. 

Microscope  No.  3,  with  stand  No.  2,  vertical  and  horizontal,  firm  stage,  coarse  and  fine  adjust- 
ment on  tube,  double  mirror,  2  objectives,  J^  j-^"  and  4  eye-pieces,  60-960  diam- 
eters ...............................................................  Price,  87X  fl.=50  thlr. 

Microscope  No.  4,  with  stand  No.  2,  simple  model,  vertical  and  horizontal,  firm  stage,  coarse 
and  fine  adjustment  on  tube,  2  objectives,  1.  1^"  and  3  eye-pieces,  60-480 
diameters  ..........................................  '.  ..................  Price,  70  fl.=40  thlr. 

Microscope  No.  5,  with  stand  No.  3,  coarse  adjustment  on  tube,  firm  on  stage,  one  objective,  1"? 
and  2  eye-pieces,  180-360  diameters  ....................................  Price,  49  fl.=28  thlr. 

Microscope  No.  6,  with  stand  No.  3,  objective,  *"  •  reduced  aperture.  2  eye-pieces,  120-240 

diameters  .........................................................  Price,  31%  fl.=18  thlr. 

Microscope  No.  7  (dissecting  microscope),  stage  with  wings,  rack  adjustment.  The  instrument 
has  3  achromatic  lenses,  forming  together  a  single  system  of  %",  focal  length  and  a  ter- 
restrial eye-piece,  magnifying  power  8,  16,  24,  40,  200  diameters  .........  Price,  56  fl.  =32  thlr. 

Microscope,  No.  7  (a  simple  dissecting  microscope),  same  mechanical  accessories,  achromatic 
lenses,  8,  16,  24  diameters  ......  ;  ...................................  Price,  24^  fl.  =  14  thlr. 

Microscope,  No.  8  (Donders'  model),  stand  like  No.  2,  rack  for  coarse  adjustment,  micrometer 
screw  for  fine,  double  mirror.  The  instrument  has  2  objectives,  -L  ^'\  and  4  eye-pieces, 
and  serves  at  same  time  as  simple  dissecting  microscope,  magnifies  8-720  diam- 
eters .................................................................  Price,  91fl.  =  52  thlr. 

B.    Microscopic  Apparatus. 

Stand  No.  1,  with  case  ...................................................  Price,  98  fl.=56  thlr. 

2,  "      ....................................................  Price,  42  fl.=24  thlr. 

"  3,  "      ...................................................  Price,  21  fl.=12  thlr. 

ObjeH-ives.  Price. 

1"  %"  %"  .........................  angle  of  aperture,  20-40°  .....................  14fl.  =  8thlr 

1-6"  ...............................   "  .........     100°  ..................  21fl.  =  12thlr. 

1-9"  1-12"  ............................   "  ............  120°.  ...................  28  fl.  =  16  thlr. 

42  fl.  =24  thlr. 
56fl.=32thlr. 

j.  .......  "  ....... 

Correcting  apparatus  increases  price  for  each  ......................................  7  fl.  =4  thlr. 

Eye-pieces  ......................................................................  5%  fl.=3  thlr. 

Eye-piece  with  micrometer  .......................................................  14  fl.=8  thlr. 

Stage  micrometer,  millimetre  in  100  parts  .......................................  10)£  n.=6  thlr. 

Screw  micrometer  ..............................................................  63  fl.=36  thlr. 

Goniometer  ...............................  "  .....................................  35  fl.=20  thlr. 

Polarizing  apparatus  ............................  _____  ...........................  28  fl.  =  16  thlr. 

Drawing  prism,  simple  ............................................................  7  fl.  =4  thlr. 

Camera  lucida,  with  double  reflection  ............................................  28  fl.  =  16  thlr. 

Compressorium  ................................  ................................  17^-  fl.=10  thlr. 

Loups,  doublets  magnifying  5,  12,  17,  24,  32  times  .................................  5^  fl.=3  thlr. 

Loupstand  ..................................  .  .  .  14  fl  .  =  8  thlr. 


............         . 

1-15"     j  ordinary  and  immer-  |  u  I    1/in  1Kno 

1-18"     1         sion  systems         j  ...............  \    14U"     JU 

*;;  immersion 


PEICE-LISTS    OF    M1CEOSCOPE    FIRMS. 


635 


No.  4. — P rice-List  of  the  Microscopes  and  Accessories  of  CARL  ZEISS,  in  Jena 

(1869). 

Price  in  Thalers. 

1.  Large  compound  microscope  (stand  0),  horse-shoe  foot,  rotary  stage,  concave    and  plane 

mirror,  freely  movable,  slider  for  changing  the  cylindrical  diaphragm  without  disturbing 
the  object,  micrometer  screw  for  fine  adjustment,  objectives  A,  B,  C,  D,  E,  P ;  4  eye 
pieces,  magnifying  20-1,500 127  thlr. 

2.  Larger  compound  microscope  (stand  16.),   horse-shoe  foot,  rotary  stage,   arched  rotary 

diaphragm,  placed  very  near  the  object,  concave  and  plane  mirror  freely  movable,  mi- 
crometer screw  for  fine  adjustment,  objectives,  A,  B,  C,  D,  E,  F  ;  4  eye-pieces ;  magnifying 
20-1,500  diameters 114  thlr. 

3.  The  same  instrument,  objectives  A,  C,  D,  P  ;    4  eye-pieces,   magnifying  20-1,500  diam- 

eters  89  thlr. 

4.  Larger  compound  microscope  (1),  round  ring-shaped  foot,  arched  rotary  diaphragm,  double 

mirror  freely  movable,  micrometer  screw,  objectives  A,  B.  C,  D,  E,  P ;  4  eye-pieces ;  20- 
1,500  diameters 106  thlr. 

5.  The  same  instrument,  objectives  A,  C,  D,  F ;  4  eye-pieces  ;  20-1,500  diameters 81  thlr. 

6.  The  same  instrument,  objectives  C,  F  ;  4  eye-pieces ;  80-1,500  diameters 64  thlr. 

7.  The  same  instrument,  objectives  B,  E  ;  4  eye-pieces ;  75-900  diameters 55  thlr. 

8.  Medium  compound  microscope  (stand  II.),  round  foot,  rotary  diaphragm,  mirror,  etc.,  as  in 

L,  objectives  C,  D,  F  ;  4  eye-pieces ;   80-1,500  diameters 70  thlr. 

9.  The  same  instrument,  objectives  B,  E  ;  4  eye-pieces ;  75-900  diameters 49  thlr. 

10.  The  same  instrument,  objectives  A,  D  ;  3  eye-pieces. 40  thlr. 

11.  Smaller  compound  microscope  (stand  III6.),  horse-shoe  foot,  the  remainder  as  in  L,  only 
somewhat  smaller ;  objectives  A,  C,  D,  F  ;  4  eye-pieces ;  20-1,500  diameters 72  thlr. 

12.  The  same  instrument,  objectives  C,  F ;  4  eye-pieces  ;  80-1,500  diameters 55  thlr. 

13.  The  same  instrument,  objectives  B,  E ;  4  eye-pieces  ;  75-900  diameters 46  thlr. 

14.  The  same  instrument,  objectives  A,  D,  3  eye-pieces 37  thlr. 

15.  Smaller  compound  microsocpe  (stand  III.  c)  ;    square,   heavy  foot,  rotary  stage,  other- 
wise like  I.,  but  smaller  ;  objectives  A,  B,  C,  D,  E,  F  :  4  eye-pieces  ;  20-1,500  diam...l04  thlr. 

16.  The  same  instrument,  objectives  A,  C,  D,  F  ;  4  eye-pieces  ;  20-1,500  diameters 79  thlr. 

17.  The  same  instrument ;  objectives  A,  C,  E ;  4  eye-pieces ;  20-to  900  diameters 60  thlr. 

18.  Smallest  compound  microscope  (Stand  IV.)  ;    round  foot ;    concave  mirror  ;  micrometer 
screw  (size  of  III.  6) ;  objectives  A,  D  ;  3  eye-pieces ;  30-740  diameters 33  thlr. 

19.  The  same  instrument ;  objective  C  ;  4  eye-pieces ;  80-330  diameters 26  thlr. 

20.  The  same  instrument ;  objective  A ;  2  eye-pieces ;  30-115  diameters 19  thlr. 

21.  Smallest  compound  microscope  (Stand  V.)  ;    objective  A;    1  eye-piece,  No.  2  or  3 ;   30-75 

or  45-115  diameters 12>£  thlr. 

22.  Smallest  compound  microscope  (Stand  V.  6) ;  micrometer  screw  on  stage  ;    objectives  A, 

D  ;  3  eye  pieces,  36-740  diameters 29  thlr. 

23.  The  same  instrument ;  objective  0  ;  4  eye-pieces ;  80-330  diameters 22>£  thlr. 

24.  The  same  instrument ;  system,  A  ;  2  eye  pieces ;  30-115  diameter 15>£  thlr. 

25.  New  preparing  microscope,  40,  60,  100  and  150  diameters 21  thlr. 

Price  of  stand  with  cases. 

Stand    0....  45  thlr.  Stand  III  c '. 22    thlr. 

1 24     "  "  IV  11      " 

1.6 32     "  "          V 6      " 

"       II 18     "  "          V.6 7^" 

"     III.  6 15     " 

Prices  and  magnifying  power  of  the  objectives. 

With  eye-piece  1234 

System  A,  upper  lens  alone 20  30  45 

A.  entire  system 50  75  115         180  5  thlr. 

B'  75  105  150         180  7 

'                     ''' 120  200         240  9 

D                                                                160  250  450         740  12 

'  240  350  600         900  18 

300  500  950  1500  25 


636  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

Eye-pieces  at 1^  thlr. 

Accessory  apparatus  for  compound  microscopes.    Eye-piece  micrometer 2-4  thlr. 

Stage  micrometer,  linm.  in  50  divisions,  in  case 2  thlr. 

Stage  micrometer  1  mm.  in  100     "          " 3  thlr. 

Stage  micrometer  X  nun.  in  100  "          "        5  thir. 

Apparatus  for  measuring  thickness  of  covers,  with  nonius  giving  1-10  mm.,  estimating  ac- 
curately 0.05  mm.,  in  case %%  tnlr- 

Camera  lucida,  after  Nachet,  in  case 5  thlr. 

Camera  lucida,  after  Nobert,  in  case '.  .5  thlr. 

Camera  lucida  of  2  prisms 7  thlr. 

Compressorium,  improved  form,  in  case 5  thlr. 

Illuminating  lens  on  stand,  3"  in  diameter,  plano-convex 12  thlr. 

do.        other  varieties 4--5-3X  thlr. 

Polarizing  microscope 10-15  thlr. 

Simple  microscope 9-19  thlr. 

Loups 18  sgr.,  to  4%  thlr. 

No.    5. — Price-List  of  Microscopes,  &c..    of  F.  W.  SCHIEK,  Berlin,  Halle1  sche 
Strasse  14  '(1870). 

Price  in  Thalers. 

A.— L.arge   Compound  Microscope,  Horse-Shoe  Stand. 

Constructed  for  inclining ;  the  stage  rotates  around  its  axis  ;  coarse  adjustment  by  rack  and 
pinion,  fine  by  micrometer  screw,  cylindrical  diaphragm  for  insertion,  with  7  objectives, 
1,  2,  4,  5,  7,  9  and  11  (immersion  system  with  correcting  apparatus)  ;  4  eye-pieces,  three  of 
which  are  achromatic ;  illuminating  lens,  insect  box,  steel  forceps,  cylindrical  loup,  eye- 
piece and  stage  micrometer,  slides,  convex  glasses,  etc.,  linear  enlargement ;  15-2,500 
times 200  thlr. 

B.— Large   Compound  Microscope,  Horse-Shoe  Stand. 

Constructed  for  inclining  ;  the  stage  rotates  on  its  axis  ;  coarse  adjustment  by  rack  and  pinion, 
fine  by  micrometer  screw,  cylindrical  diaphragms,  six  objectives,  1,  3,  5,  7,  9  and  10 
(immersion  system) ;  4  eye-piecer,  two  of  which  are  achromatic ;  illuminating  lens,  eye-piece 
and  stage  micrometer,  etc. ;  magnifying  from  15-1,800  times  linear 150  thlr. 

C.— Medium  Compound  Microscope,  Horse-Shoe  Stand. 

a.  Not  constructed  for  inclining ;  stage  rotates  on  its  axis ;  coarse  adjustment  by  rack  and 
pinion,  fine  by  micrometer  screw;  cylindrical  diaphragms;  5  objectives,  1,  3,  5,  7  and  9  ; 
4  eye-pieces,  one  of  which  is  achromatic  ;  illuminating  lens,  etc.  ;  giving  20-1,500  times 
linear 100  thlr. 

6.  The  same  model,  with  3  eye-pieces  and  4  objectives,  3,  5,  7  and  9  ;  without  illuminating  lens ; 

giving  50-1,200  times  linear 80  thlr. 

!>.— Medium  Compound  Microscope,   Stand  with   Folding  Tripod. 

Coarse  adjustment  by  rack  and  pinion,  fine  by  micrometer  screw,  which  tilts  the  stage  ;  stage 
not  rotary  ;  cylindrical  diaphragms  ;  4  objectives,  3,  5,  7  and  9 ;  4  eye-pieces ;  illuminating 
lens,  etc.,  giving  50-1,500  times  linear 100  thlr. 

E.— Compound    Microscope,   Horse-Shoe    Stand. 

Constructed  to  incline ;  rotary  stage,  micrometer  screw,  rotary  diaphragm ;  4  objectives,  3, 
5,  7  and  8;  4  eye-pieces;  illuminating  lens,  50-860  linear 75  thlr. 

F.— Compound  Microscope,  Horse-Shoe  Stand. 

a.  Firm  stage,  not  rotary,  micrometer  screw,  rotary  diaphragm ;  4  objectives,  1,  3,  5,  7  ;  3  eye- 
pieces ;  30-600  linear 50  thlr. 

ft.  The  same  model,  with  objectives  3,  5,  7,  and  9 65  thlr. 

If  rotary  stage  is  desired,  price  is  increased 10  thlr. 

G.— Small  Compound  Microscope,  Horse-Shoe  Stand. 

Immovable  stage,  micrometer  screw,  rotary  diaphragm  ;   3  objectives,  3,  5,  7  ;    2  eye-pieces  ; 

50-450  linear , gg  thlr. 

H.— Small  Compound  Microscope,  Drum   Stand. 

Micrometer  screw  on  stage,  rotary  diaphragm,  3  achromatic  objective  lenses,  1+2+3  (system 
4)  ;  and  objective  7 ;  2  eye-pieces,  etc. ;  25-500  linear , ...  28  thlr. 


PEICE-LISTS    OF    MICROSCOPE    FIEMS. 


637 


I.— Small    Compound   Microscope,  for  the  Use  of  School*. 

a.  Micrometer  screw,  rotary  diaphragm,  3  achromatic  objective  lenses,  1+2+3  (system  4) ; 

and  objective  7  ;  two  eye-pieces  ;  forceps,  slides  and  covers,  40-450  linear 25  thlr. 

6.  The  same  model,  with  two  achromatic  objective  lenses,  1+2,  and  objective  5 ;  one  eye- 
piece, etc.,  40-300  linear 20  thlr. 

c.  Tha  same  model  with  cast-iron  foot ;  stage  without  diaphragm,  2  objectives,  1+2  and  5 ; 
one  eye-piece,  ecc 15  thlr. 

K.— Smallest    C  ompound     Microscope,    Travelling  Pocket  Micro- 
scope. 

The  stand  is  constructed  to  fold  together,  with  one  eye-piece  and  one  objective,  consisting  of 

three  achromatic  lenses,  magnifying  200  times  linear 10  thlr. 

N,B.— This  microscope,  which  is  especially  adapted  for  foot  travelling,  is  enclosed  in  a  case 
4"  long  by  2%"  wide  and  \%"  deep. 

I,.— Simple    A  chroma  tic    Microscope,  Simplex. 

In  a  mahogany  case,  with  6  achromatic  lenses,  in  two  systems,  magnifying  40  times  linear. 20  thlr. 

M.—  The  several  Objectives  and  their  Average   Magnifying  Power 
\\ith    the   Various   ICyc- Pieces. 


OBJECTIVE. 

O 

1 

2 

3 

Price. 

^o  i                     

20 

35 

5   thlr 

2          

45 

65 

. 

- 

6 

3                    

70 

100 

180 

ty& 

4         

90 

125 

210 

8 

5              

150 

220 

350 

9 

g                          

200 

300 

450 

550 

10 

7          

260 

375 

550 

650 

10 

8                       

400 

550 

700 

960 

12 

9            

450 

700 

900 

1,200 

16 

*    '    9                  

500 

750 

1,100 

1.500 

25 

*    '  10                           .     • 

600 

800 

1  200 

1,800 

30 

#    '11                

750 

1,000 

1,400 

2,500 

40 

*  Nos.  9, 10,  and  11  are  immersion  systems  with  simple  correcting  apparatus.  If  double  correct- 
ing apparatus  (an  arrangement  by  which  the  position  of  all  three  lenses  may  be  changed  with 
screw)  is  required,  the  price  is  increased  10  thalers  each. 

No.  G.— Price-List  of  E.  GUNDLACH,  Berlin,  1870. 

Price  in  Thalers. 
Microscopes. 

1.  Large  binocular  stereoscopic  microscope.      Large  brass  foot  with  two  massive  arms  on 

which  the  body  rests.  It  may  be  inclined  from  vertical  to  horizontal.  The  body  may 
also  be  rotated  around  the  optical  axis  without  moving  the  illuminating  apparatus. 

The  stereoscopic  double  tube  may  be  removed  and  replaced  by  a  simple  tube.  The  dis- 
tance between  the  two  stereoscopic  eye-pieces  may  be  adapted  by  an  adjusting  mechanism 
to  the  distance  between  the  eyes.  The  tube  has  three  arrangements  for  adjustment :  the 
rapid  movement  (coarse  adjustment)  by  rack-work ;  the  medium,  for  fine  adjustment,  for 
powers  below  500  diam. ;  and  the  extremely  slow  adjustment  for  the  highest  powers.  The 
last  two  movements  are  without  friction,  and  are  combined  with  new  and  desirable  im- 
provements. 

The  diaphragm  is  placed  on  a  slider,  so  that  it  may  be  entirely  removed  from  the 
instrument  if  necessary  (6  cylinder  diaphragms).  Large  double  mirror,  freely  movable. 
Stage  inlaid  with  glass. 

To  this  instrument  belong :  a  stase,  which  is  movable  by  means  of  fine  screws,  and  which 
may  be  removed  and  replaced  at  pleasure  (No.  22) ;  a  revolving  nose  piece  for  five  objec- 
tives (No.  21 ),  fitting  the  ordinary  as  well  as  the  double  tube ;  eye-piece  micrometer,  ad- 
justing with  fine  screws  (No.  20) ;  a  polarizing  apparatus  with  goniometer  (No.  18) ; 
Oberhauser's  drawing  apparatus  (No.  16) ;  large  illuminating  lens  for  opaque  objects  (No. 
23) ;  an  achromatic  condenser ;  compressorium  (No.  26) :  stage  micrometer  (No.  27). 

The  objectives  Nos.  I,  II,  IV,  V,  VI6,  VII6,  VIII,  and  IX ;  3  eye-pieces  (magnifying 
30-2300-fold),  test  objects,  slides,  covers,  etc. ;  all  in  a  strong  mahogany  case,  bound  with 
brass,  and  arranged  for  convenience  in  carrying  ;  lenses  in  a  separate  leather  case 362  thlr. 

2.  Large  microscope.     Rotary  stage  with  divisions,   and  adjusting  screws  for  correcting  the 

centring;  joint  for  inclining ;  draw-tube ;  large  brass  foot;  coarse  adjustment  by  rack 
work,  fine  by  micrometer  screw ;  freely  movable  double  mirror ;  4  cylindrical  diaphragms 
with  slide-movement;  nose-piece  for  4  objectives;  movable  stage;  movable  eye-piece 


638  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

micrometer ;  polarizing  apparatus  with  goniometer ;  Oberhauser's  drawing  apparatus : 
large  illuminating  lens ;  condenser,  etc.  Objectives  No.  I,  II,  IV,  V,  VI6,  Vllft,  and 
IX  ;  3  eye-pieces ;  power  30-2300  fold ;  test  objects,  slides,  covers,  etc.  ;  lenses  in  leather 
case.  The  whole  in  mahogany  case 252  thlr. 

The  same  instrument,  with  objectives  Nos.  I,  II,  IV,  V,  VI6,  and  VIII 215  thlr. 

The  same  instrument  with  the  following  accessories:  nose-piece  for  4  objectives :  polarizing 
apparatus  with  goniometer  ;  Oberhauser's  drawing  apparatus  ;  valuable  eye-piece  micro- 
meter :  condenser,  etc.  Objectives  Nos.  I,  II,  IV,  V,  and  VII6 ;  3  eye-pieces,  magnifying 
30-1150  times ;  test  objects,  slides,  covers,  etc .168  thlr. 

The  same  instrument  without  accessories :  objectives  Nos.  I,  II,  IV,  V,  and  VII& ;  3  eve- 
pieces,  last  with  micrometer ;  condenser,  test  objects,  slides,  and  covers 122  thlr. 

3.  Medium  microscope,  with    joint  for  inclining  like  No.  2;    rotary  stage  with  centring 

screws  :  heavy  brass  foot :  coarse  adjustment  by  rack- work,  fine  screws  (without  friction) ; 
3  cylinder  diaphragms  ;  sliding  apparatus ;  freely  movable  double  mirror ;  objectives  Nos. 
I,  II,  IV,  V,  and  VII&  ;  3  eye-pieces  ;  one  micrometer  for  insertion ;  30-1500  diam.  ;  con- 
denser, etc.  In  strong  mahogany  case 100  thlr. 

4.  Medium  microscope,  with  joint  for  inclining,  heavy  brass  foot :   3  cylinder  diaphragms, 

freely  movable  double  mirror :  immovable  stage  ;  fine  adjustment ;  objectives  Nos.  I,  II, 
IV.  V,  and  VII&J;  3  eye-pieces  and  micrometer ;  condenser,  etc. ;  magnifying  power  30-1500 

fold.     Mahogany  case,  etc 88  thlr. 

The  same  instrument,  with  objectives  Nos.  I,  III,  V,  Vila  ;  3  eye-pieces,  and  micrometer,  con- 
denser, etc.  ;  magnifying  30-1150  fold 76  thlr. 

5.  Medium  microscope,  without  joint  for  inclining  ;  brass  foot,  filled  with  lead ;  3  cylinder  dia- 

phragms without  slider  ;  double  mirror  :  fine  screw  adjustment ;  objectives  Nos.  I,  III.  V. 

and  Vllft ;  3  eye-pieces,  and  micrometer,  condenser,  test  objects,  etc. ;  magnifying  30-1150 

fold.     Mahogany  case,  and  leather  case  for  lenses 76  thlr. 

The  same  instrument,  with  objectives  Nos.  I,  III,  V,  and  Vila ;  3  eye-pieces,  and  micrometer, 

test  objects,  case,  etc. :  magnifying  30-1150  fold 69  thlr. 

The  same  instrument,  with  objectives  Nos.  II,  V,  and  Vila ;  2  eye-pieces,  test  objects,  caso, 

etc. ;  magnifying  70-1150  times 61  thlr. 

The  same  instrument,  with  objectives  Nos.  I,  III,  and  V ;   2  eye-pieces,  and  micrometer,  test 

objects,  etc. ;  magnifying  power  30-500  fold 50  thlr. 

Case,  1  thlr.  more. 
The  same  instrument,  with  objectives  Nos.  II  and  V ;   2  eye-pieces  and  micrometer ;  70-500 

times 45  thlr. 

6.  Travelling  microscope,  with  folding  tripod  and  draw-tube  under  stage  for  increasing  the 

length  of  the  instrument ;  screw  for  fine  adjustment ;  objectives  Nos.  II,  V,  and  Vila ; 
2  eye-pieces  and  micrometer,  test  objects,  etc.  ;  magnifying  70-1150  times.  The  whole  in 

a  mahogany  case  21  ctmetrs.  long,  12  ctmetrs.  wide,  and  8  ctmetrs.  high 60  thlr. 

The  same  instruments  with  objectives  Nos.  I,  III,  and  V ;  2  eye-pieces ;  micrometer,  test  ob- 
jects, etc.  ;  magnifying  300-500  times 50  thlr. 

7.  Simple  microscope,  round  brass  foot,  fine  adjustment  by   screw  on  stage ;    rotary  dia- 
phragm,  concave   mirror  ;   objectives  No.  II  and  V  ;    2  eye-pieces  and  diaphragm,  test 
objects,  etc. ;  magnifying  70-500  times  ;  mahogany  case 32  thlr. 

8.  Small  microscope,  round   foot,  fine  adjustment  on  stage  :    concave  mirror ;    objectives 

II  and  V  ;    2  eye-pieces  ;    test  objects,  etc.  ;  magnifies  70-500  times  ;   mahogany  case. . 26  thlr. 
The  same  instrument,  with  3  achromatic  objective  lenses,  and  1  eye-piece ;  magnifying  60, 

100,  and  180  times .16  thlr. 

9.  Demonstrating  microscope  (when  the  preparation  is  fastened  in  may  be  passed  from  hand 

.  to  hand) :  3  achromatic  objective  lenses,  and  1  eye-piece :    magnifies  40,   80,  and  120 
times : ' 12  thlr. 

10.  Micro-photographic  apparatus,  adjustable  to  any  stand 36  thlr. 

The  same  apparatus,  with  the  micro-photographic  objectives  \£,  %,  and  1  in.  focus f;9  thlr. 

11.  Large  micro-photographic  apparatus,  to  be  used  without  any  microscope  stand;     size 

of  image  15  ctmetree  diameter,  with  the  micro-photographic  objectives  %,  %,  and  1  in. 
focus 116  thlr. 

12.  Large  horizontal  micro-photographic  apparatus :     may  be  drawn  out  to  a  length  of  2 

metres ;  size  of  image,  30  ctmetres  :  with  the  micro-photographic  objectives  i£,  ^.  % 
and  1  in.  focus,  and  the  immersion  objective  No.  Vila 192  thlr. 

Accessory  Apparatus. 

13.  Preparing  microscope    (simplex)  :    firm  stage ;    adjustment  by  rack-work,  on  a  polished 

mahogany  case,  with  rests  for  the  hands,  and  2  "drawers  ;  2  achromatic  triplets 15  thlr. 

The  same  instrument,  with  3  triplets 18  thlr. 

The  same  instrument,  with  folding  case  (compact  for  travelling),  with  3  triplets 20  thlr. 

7  4.  Large  stand  lonp,  with  heavy  brass  foot  and  a  long  double-jointed  arm  ;  2  lenses  of  40 

mm.  diameter ;  magnifying  3  and  (5  times 6  thlr. 

15.  Small  stand  loup  ;    arrangement  as  in  No.  14 ;  2  lenses  of  25  mm.  diameter  ;  magnifying 

5  and  10  times 33^  thlr. 

16.  Drawing  apparatus,  after  Oberhauser   ...  10  thlr. 


PEICE-LISTS    OF    MICEOSCOPE    FIRMS. 


639 


17.  Goniometer 20  thlr. 

18.  Polarizing  apparatus,  with  goniometer,  after  Hartnach  (improved) 20  thlr. 

19.  Simple  polarizing  apparatus  (analyzer  over  eye-piece) 14  thlr. 

20.  Movable  eye-piece  micrometer,  in  a  special  eye-piece,  with  a  fine  screw  for  horizontal 

movement,  and  correction  for  sharp  adjustment 8  thlr. 

Simple  eye-piece  micrometer 2  thlr. 

21.  Nose-piece  for  5  objectives 10  thlr. 

The  same,  smaller,  for  4  objectives 8  thlr. 

22.  Movable  stage  (with  5  screws) , .8  thlr. 

23.  Large  illuminating  doublet  for  opaque  objects,  on  a  separate  stand,  with  heavy  brass  foot  8  thlr. 

24.  Simple  illuminating  lens,  on  stand 4  thlr. 

25.  Max  Schultze's  warm  stage 10  thlr. 

26.  Compressorium 5  thlr. 

27.  Stage  micrometer,  in  case ;  1  mm.  in  100  parts 3  thlr. 


Objectives    and   Eye-Pieces, 


OBJECTIVES. 

FOCUS. 

AXGLE  OF 
APEKTUBE. 

Thlr. 

No     I 

Inches. 
1 

Degrees. 
13 

5 

II 

1-2 

38 

5 

III 

1  3 

50 

5 

IV 

1-4 

80 

8 

V 

1-8 

150 

10 

VI  a 

1-12 

170 

Without  correcting  screw  

15 

VI  & 
Vila 
VII  & 
VIII 
IX 

1-12 
1-16 
1-16 
1-24 
1-32 

170 
175 
175 
175 
175 

With               "•             "     
Immersion,  without  correcting  screw  .  .  . 
with                               "     ... 

20 
15 
20 
30 
45 

Micro-photographic  objective,  1  in.  focus 12  thlr. 

Micro-photographic  objective,  %  in.  focus 10  thlr. 

Micro-photographic  objective,  %  in.  focus 10  thlr. 

Micro  photographic  objective,  %  in.  focus 15  thlr. 

Eye-pieces,  No.  0,  I,  II,  and  III at  2X  thlr. 

Eye-piece,  No.  Ill,  with  micrometer 4  thlr. 

Periscopic  eye-piece  (larger  and  more  level  field),  No.  0 7  thlr. 

Periscopic  eye-piece  (larger  and  more  level  field),  No.  1 6  thlr. 

Periscopic  eye-piece  (larger  and  more  level  field),  No.  2 5  thlr. 

Periscopic  eye-piece  (larger  and  more  level  field),  No.  3 5  thlr. 

New  objective  No.  X. ;    focus,  1-50  in. ;  angle  of  aperture,  175°  ;  magnifying  power,  1,260, 

1,800  2,500,  and  3,400  fold 100  thlr. 


Magnifying  Powers. 


NO.  OF  OBJECTIVE. 

I 

II 

III 

IV 

V 

VI 

VII 

VIII 

IX 

20 

45 

65 

95 

190 

315 

420 

630 

'  840 

30 

65 

90 

138 

275 

450 

600 

900 

1200 

45 

90 

125 

185 

375 

625 

835 

1250 

1670 

Eye-piece  III 

65 

120 

170 

250 

500 

830 

1150 

1700 

2300 

640  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

^Vb.  7. — Price-List  of  L.  Heneche,  Berlin,  Grossbeeren  Strasse,  No.  17.  (1870). 

Price  in  Tfialers. 
Compound    Microscopes. 

A.  Horse-shoe  foot :  slider  for  changing  the  diaphragms  ;  large  rotary  stage  ;  micrometer  ad- 

justment on  the  tube;    objectives  2,  4,  7,  9.  10,  11,  12:     eye-pieces  1  to   5 ;    adjustable 
eye-piece  micrometer ;  condenser ;  magnifying  3,000  diameters 230  thlr. 

B.  Stand  similar  to  that  of  A,  but  smaller  :  objectives  4,  7,  9,  10  ;    eye-piece  1  to  4 ;    eye-piece 

micrometer ;  condenser ;  magnifying  300  diameters 100  thlr. 

C.  Horse-shoe  foot:  large  firm  stage:  slider  for  changing  the  diaphragms;  micrometer  adjust- 

ment on  tube ;  objectives  4,  7,  9  ;    eye-pieces  2,  3.  4 ;    eye-piece  micrometer ;    magnifying 

power  600 50  thlr. 

The  same  microscope,  with  objectives  4,  7,  10  ;  giving  800  diameters 60  thlr. 

D.  Round  foot,  micrometer  adjustment  on  tube ;  arched  diaphragm  under  the  stage  ;  objec- 

tives, 4,  7 ;  2  eye-pieces ;  magnifying  400  diameters 25  thlr. 

The  same  microscope,  with  objectives  4,  7,  8 ;  magnifying  500  diameters 30  thlr. 

The  same  microscope,  with  objectives  4,  7,  9 ;  magnifying  500  diameters 37  thlr. 

Smaller    Microscopes. 

(I.  Round  foot :  micrometer  adjustment  on  stage  ;  diaphragm  under  stage  ;  eye-piece  micro- 
meter ;  2  eye-pieces ;  6  different  magnifying  powers  to  400  diameters 15  thlr. 

E.  Round  foot ;  micrometer  adjustment  on  stage ;  1  eye-piece ;  3  different  magnifying  powers 

to  300  diameters..  - 

Price  of  the  Objectives. 

No.  1 ..  4  thlr.     No.  8...  ...10  thlr. 

2 5  "  9 12 

3 6  "  10 ..  (immersion  with  correction) 25 

4 7  "  11 15 

5 8  "  11 ..  (with  correction) 20 

6 10  "  12.  .(immersion  with  correction) 50 

7 10  " 

No.  8. —  Price- List  of  the  Achromatic  Microscopes  of  the  Institute  founded  in 
Wetzlar  by  C.  KELLNER,  Successor  ERNST  LEITZ  (formerly  BELTHLE  & 
LEITZ,  1870. 

Price  in  Thalers. 
Microscopes. 

1.  Large  microscope.  Coarse  adjustment  by  rack  and  pinion,  fine  by  micrometer  screw :  slid- 
ing arrangement  for  cylinder  diaphragms;   polarizing  apparatus;   drawing  apparatus: 
eye-piece  micrometer;   double  mirror;   rotation  on   the  optical  axis;   orthoscopio  eye 
pieces  I,  II,  III,  IV,  and  objectives  1,  2,  3,  5,  6,  7,  and  immersion  Nos.  8  and  9.    20--2000 
diameters 150  thlr. 

The  same,  to  incline 1GO  thlr. 

2.  Medium  microscope ;  stand  as  in  No.  1 ;  eye-piece  micrometer ;  4  orlhoscopic  eye-pieces  : 
objectives  1,  3,  5.  7,  and  immersion  9  ;  20-1500  diam 100  thlr. 

3.  The  same  stand,  but  without  rotation  on  optical  axis ;  3  eye-pieces ;  objectives  1,  3,  7  and 

9 :  immersion,  25-1500  diam 80  thlr. 

The  same,  without  immersion  system  9 65  thlr.' 

4.  Small  microscope.  Horse-shoe  foot :  rotation  on  optical  axis  :  fine  adjustment,  micrometer 
screw,  double  mirror  ;  cylindrical  diaphragms  ;  3  eve-pieces  :  objectives  1,  3,  7.  and  immer- 
sion 8 ;  magnifying  25,  40,  60.  75,  100,  140,  220,  350,  500,  600,  800,  1000 60  thlr. 

5.  Small  microscope :  No.  4  stand  ;  double  mirror ;  3  eye-pieces  ;  objectives  2.  5,  7  ;  magnifying 

35,  60,  100,  120,  200.  300.  320,  500.  800 '. .......... .50  thlr. 

6.  Small  microscope :   stand  like  No.  4,  but  smaller ;  rotation  on  optical  axis,  cylinder  dia- 
phragms ;   3  eye-pieces ;   objectives  1,  3,  7 ;   magnifying  20,  30.  50.  60,  100,  130,  300,  450 

600 : 40'thlr. 

7.  The  same  microscope,  without  rotation 35  thlr. 

8.  Small  microscope ;  fine  adjustment  by  micrometer  screw  on  tube ;  eye-piece  micrometer  • 

3  eye-pieces;  objectives  1,  3,  7 ;  magnifying  20,  30,  SO,  60,  100,  130,  300,  450,  600 30  tnlr. 

9.  Same  stand  as  No.  7;   2  eye-pieces;   objectives  1,  3,  7 :   magnifying  20,  30,  60,  100,  300. 
500 ...  25  thlr- 


PEICE-LISTS    OF   MICROSCOPE    FIRMS. 


641 


10.  Smallest  microscope ;  2  eye-pieces ;  objectives  3,  7 ;  magnifying  60-500 20  thlr. 

The  same,  without  objective  No.  7 15  thlr. 

11.  Laboratory  microscope,  after  A.  Stuart.    Coarse  adjustment  by  sliding  on  a  square  metallic 
column ;  fixation  of  same  by  means  of  a  screw  ;  tine  adjustment  by  micrometer  screw  on 
tube ;  eye-piece  micrometer ;  2  eye-pieces  ;  objectives  1,  3,  7 ;  magnifying  from  25-500.  .30  thlr. 

The  same,  with  drawing  and  polarizing  apparatus 42  thlr. 

12.  Laboratory  microscope,  with  stand  like  No.  10  ;  one  eye-piece  ;  objectives  3,  6 23  thlr. 

The  same,  with  drawing  and  polarizing  apparatuses,  and  eye-piece  micrometer 37  thlr. 

!?.£. — All  microscopes  are  enclosed  in  a  compact  mahogany  case  with  lock.    Magnifying 

powers  of  the  microscopes  are  calculated  at  8  in.  =  216  mm. 

NEW  SYSTEMS,  WITH  LAEGE  ANGLES  OP  APERTURE. 


EYI 

:-PIECES. 

I, 

* 

I. 

II. 

III. 

'•3  S 

"3  c 

• 

t 

to 

I. 

II. 

III. 

IV. 

V. 

r 

No.  0  

No.  1  .  . 

20 

25 

35 

40 

50 

60 

30 

"  0  a 

"  2 

35 

50 

60 

70 

85 

100 

17  5 

"  1  

•'  3.  ... 

6t> 

75 

90 

100 

115 

140 

5  5 

"  la. 

"  4 

85 

115 

140 

150 

170 

220 

3  5 

2  

2a. 

"  5  

"  6 

120 
180 

150 
220 

175 
320 

200 
350 

220 
380 

300 
500 

1.8 
1  45 

3 

"  7 

250 

320 

450 

500 

•  650 

800 

1  06 

3«. 

"  8  .. 

350 

500 

600 

650 

750 

970 

0  98 

4. 

"  9 

450 

650 

750 

850 

1  000 

1  450 

o  $ 

5... 

"  10.. 

500 

700 

900 

1.150 

iAOO 

1.8UO 

0.6 

8 
10 

5?' 

12 
15 
18  J 


NEW  IMMERSION  OBJECTIVES  WITH  CORRECTION. 


"  8  

350 

450 

550 

650 

800 

1,000 

0.93 

15 

"  9 

450 

650 

750 

850 

1,000 

1,450 

0.8 

20 

"  10.'.'.".'.'.'. 

500 

700 

900 

1,200 

1,500 

2,000 

0.6 

25 

No.  9. — Price-List  of  the  Microscopes  of  BRUNO  HASERT,  in  Eisenach  (1867). 

Price  in  Thaler s. 

Large  stand  with  rotary  stage  for  direct  and  oblique  illumination,  with  achromatic  condensing 
lens  for  slightly  oblique  light,  with  three  eye-pieces,  and  an  illuminating  lens  for  opaque 
objects 45-50  thlr. 

Small  stand  with  rotary  stage,  achromatic  condensing  lens,  and  illuminating  lens  for  opaque 
objects,  with  2  eye-pieces 25-27  thlr. 

Small  stand  without  rotary  stage,  cylindrical  diaphragm,  and  oblique  illumination,  illumina- 
ting lens  for  opaque  objects,  and  two  eye-pieces .15  to  17  thlr. 

A.  Objective  of   the  first  quality,  of   1-16  in.  focus,  which,  without  immersion,  thoroughly 

resolves  all  known  test  objects 45  thlr. 

B.  Objective,  first  quality,  1-12  in.  focus,  which  also  shows  the  hexagons  on  the  Pleurosigma 

angulatum,  and  also  the  striations  on  the  Grammatophora  snbtilissima,  without  im- 
mersion  35  thlr. 

C.  Objective,  first  quality,  1-5  in.  focus,  which  also  shows  without  immersion  the  hexagons  on 

the  Pleurosigma  angulatum 20  thlr. 

D.  Objective,  second  quality,  of  shorter  focus,  which  shows  the  transverse  striations  on  the 

butterfly's  scales,  and  the  striations  of  the  Pleurosigma  attenuatum ;  by  unscrewing  the 
frost  lens  a  lower  power  is  obtained 8-10  thlr. 

The  price  of  the  neveral  stands  and  objectives  may  be  readily  calculated  from  the  above,  as,  for 
instance,  microscope,  first  rank,  with  objectives  A,  C,  and  D,  giving  from  60-2,400 
linear 125  thlr. 

Microscope  with  rotary  stage,  small  model,  with  objectives  B  and  D,  sufficing  for  the  most 
difficult  examinations,  giving  100-1,500  linear 75  thlr. 

The  same,  with  objectives  C  and  D 60-65  thlr. 


*  Old  designation  of  objectives  and  eye-pieces. 
t  New  designation  of  objectives  and  eye-pieces. 

41 


642  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

Small  stand  with  rotary  stage,  with  objectives  C  and  D,  sufficing  for  most  examinations,  600- 
700  linear 36-50  thlr. 

The  small  microscope  with  two  eye-pieces  and  one  objective,  the  front  lens  of  which  unscrews, 
and  thus  forms  a  second  objective,  giving  power  up  to  400 25-27  thlr. 

N.B. — The  best  objectives  are  to  be  used  without  immersion,  give  unclouded  and  clear  images, 
and  the  strongest  do  not  need  correction  for  covers. 

No.   10.— Price-list  of    Optical  Institute  of  S.  PLOSSL  &  Co.,  in    Vienna 

(1871). 

Factory,  Depot, 

Wieden,  Theresianumgasse,  No.  12.  Stadt,  Eauhenstein  &  Himmelpfortgasse,  7. 

Price  in  Guldens. 
Complete    Microscopes. 

1 .  Large  compound  microscope,  tube  moved  by  rack-work,  micrometer  screw  for  fine  adjust- 

ment, stage  covered  with  glass,  brass  pedestal,  microscope  moves  on  one  arm  on  its  axis, 
stage  has  two  clamps  for  holding  all  sorts  of  slides,  Ireely  movable  mirror  on  a  double 
arm,  sliding  arrangement  for  cylinder  diaphragms.  The  instrument  is  furnished  with 
six  achromatic  objectives,  so  arranged  as  to  be  used  with  or  without  covers  ;  three  eye- 
pieces, magnifying  from  25-600  times  linear,  or  625-c60,000  superficial ;  spherical  illumina- 
ting prism  (after  Selligne),  with  movement  for  illuminating  opaque  objects,  large  con- 
densing lens  (to  use  with  lamp-light)  on  a  separate  stand,  slices,  a  Wilson's  loup,  two 
micrometers  with  divisions  of  the  Vienna  duodecimal  line  into  30  and  60  parts,  or  the 
millimetre  into  25  and  50  parts,  mounted  in  brass,  for  insertion  into  the  eye-piece  No.  2, 
with  screw  for  adjustment.  Polished  case,  lined  with  velvet,  with  lock  and  key 210  fl. 

2.  The  same  with  arrangement  for  measuring  objects  to  0.00001  Paris  lines,  by  means  of 

Fraunhofer's  screw  micrometer 300  fi. 

3.  Medium  compound  microscope,  presenting  the  same  advantages  as  No.  1,  but  smaller..  .200  fl. 

4.  Medium  compound  microscope,  rack-work  to  move  tube,  micrometer  screw  for  fine  adjust- 

ment, immovable  stage  covered  with  glass,  two  clamps  on  stage  to  hold  slides,  concave 
mirror  on  a  double  arm,  freely  movable  ;  three  achromatic  objectives,  so  arranged  as  to 
be  used  with  or  without  covers ;  three  eye-pieces,  magnifying  25-600  times  linear  :  illumi- 
nating lens  for  opaque  objects,  slides  on  a  Wilson's  loup,  two  eye-piece  micrometers  with 
screws  for  adjusting,  mill  metre  divided  into  25  and  50  parts,  mounted  in  brass.  Polished 
case,  lined  with  velvet,  lock,  etc., 130  fl. 

5.  Small  microscope,  micrometer  screw  on  stage,  movable  concave  mirror,  ordinary  rotary 

diaphragm,  new  objective  C,  and  2  eye-pieces ;  magnifies  60-120  times.  Elegant  polished 
case 52  fl. 

6.  Small  microscope,  exactly  like  No.  5,   objective  E,  and  two  eye-pieces ;  magnifies  180-360 

times 64  fl. 

7.  Small  microscope,  like  No.  5,  coarse  adjustment  by  rack- work,   with  objectives  C  and  E, 

and  two  eye-pieces  ;   magnifies  60,  120,  180  and  360  times  linear.   75  fl. 

8.  New  small  working  microscope,  on  a  round  brass  foot,  the  body  resting  on  a  horizontal 

arm ;  stage  has  two  clamps  for  slides,  and  moves  by  rack-work  towards  the  objectives  ; 
movable  concave  mirror,  slides,  etc.,  one  eye-piece  and  three  achromatic  objectives  ;  mag- 
nifies from  20-150  times  linear,  made  gradual  by  elongating  the  tube.  The  microscope  is 
BO  arranged  that  the  objects  do  not  appear  inverted,  is  therefore  a  very  convenient  in- 
strument for  dissecting.  Elegant  polished  case 54  fl. 

9.  New  large  working  microscope,  body  moves  by  rack-work  towards  the  immovable  stage ; 

otherwise  like  No.  8 ;  magnifies  to  300  linear 70  fl. 

10.  Small  travelling  microscope,  with  a  stand  to  be  screwed  into  the  cover  of  the  case,   stage 
with  clamps,  to  be  moved  by  rack-work  towards  the  lenses  ;  concave  mirror  with  double 
movement,  slides,  needles,  forceps,  etc.,  six  mounted  double  lenses,  after  Wallaston,  mag- 
nifying from  12-250  times  linear.    Polished  case,  lined  with  velvet 60  fl. 

11.  The  same  microscope  with  3  double  lenses 36  fl. 

12-        do-  "    6  simple      "     45  fl. 

13.  do.  "    3        "         «     SOfl. 

14.  Microscope,  heavy  foot,  immovable  stage,  fine  adjustment  by  micrometer  screw,  rotnry 
diaphragm,  lateral  movement  to  mirror  ;  one  eye-piece  and  objective,  magnifies  500  linear"; 
excellently  adapted  for  examining  silk  disease. 

Sun,  gas  and  photo-electric  microscopes  made  to  order. 

Microscopic    Accessories. 

15.  Ordinary  eye-pieces,  1.  2,  3,  4,  5 @,  5  fl. 

Orthoscopic  eye-pieces,  1,  2,  3,  4,  5 @,  8  fl. 

Aplanatic  "         10-50  fl. 

Solid  glass          "        ...8fl. 


PRICE-LISTS    OF    MICROSCOPE    FIRMS.  643 

16.  Achromatic  objectives  wth  large  angles  of  aeprture. 

A.  Combination  of  3  achromatic  lenses  designated  1,  2,  3 15  fl. 

B.  do.  "          "  "  "  4,5,6 18  fl. 

C.  System,  1-3" 10  fl. 

D.  "        1-6" 18  fl. 

E.  "        1-9" 24  fl. 

F.  "        1-12",  correcting  apparatus 35  fl. 

G-.        ••        1-18"  "  "         60fl. 

17.  Stage  screw  micrometer 90  fl. 

18.  Eye-piece  "  60  fl. 

19.  Micrometer  eye-piece 8  fl. 

20.  Eye-piece  micrometer 5  fl. 

21.  Stage  "  6fl. 

22.  Goniometer 28  fl. 

38.  "        with  polarizing  apparatus  , 45  fl. 

24.  Polarizing  apparatus,  A,  over  objective  ;  P.  under  stage 24  fl. 

25.  "        A,  over  eye-piece ;  P.        "        "     28  fl. 

26.  Wallaston:s  camera  lucida 12-20  fl. 

27.  Sommering's  speculum  apparatus 12  fl. 

28.  Warm  stage 18  fl. 

29.  Compressorium,  after  Purkinje 15  fl. 

SO.  "  "        Plossl 12  fl. 

31.  Prism  for  horizontal  vision 18  fl. 

32.  Electrical  discharger,  after  Plossl 9  fl. 

33.  Spherical  illuminating  prism,  after  Selligue 15  fl. 

34.  Illuminating  lens  on  stand 12  fl. 

No.  11. — Price- List  of  the  Microscopes,   etc.,  of  THOMAS  Boss,    Optician,  7 

Wiymore  street,  Cavendish  Square.  London,  W.  (1872). 

Price  in  £  s.  d. 

Compound    Microscopes. 

£   s.  d. 

No.  1.  A  large  compound  microscope  stand,  with  graduated  concentric  rotating  stage, 
having  one  inch  of  motion  in  rectangular  directions  ;  rack  and  fine  screw  movements 
to  the  optical  part,  clamping  arm  for  fixing  the  instrument  at  any  inclination,  gradu- 
ated sub-stage  for  holding  and  adjusting  by  universal  motions  all  the  illuminating  and 
polarizing  apparatus  placed  beneath  the  object;  2  eye-pieces,  flat  and  concave  mirrors ; 

diaphragm  plate ;  stage  forceps,  and  two  glass  plates  with  ledges 30    0  0 

No,  2.  A  smaller  microscope  stand,  having  three-quarters  of  an  inch  of  motion,  and  ordi- 
nary rotating  object  plate  to  the  stage 21  10  0 

No.  2  A  ditto,  without  sub-stage 17    00 

No.  2.  A  microscope  stand  without  sub-stage ;  fine  screw  adjustment,  or  stage  move- 
ments ;  with  2  eye-pieces,  a  one-inch  object  glass  of  25  degrees  angular  aperture, 
and  a  one-quarter  inch  object-glass  of  100  degrees — this  is  the  basis  of  a  complete  in- 
strument   18  11  0 

No.  2.  Mechanical  stage  for  do 4  10  0 

No.  2.  Fine-screw  adjustment  for  ditto 2  14  0 

No.  2.  Sub-stage  and  vertical  rack  motion  for  ditto 4  10  0 

No.  3.  A  smaller  microscope  stand,  with  mechanical  stage  and  fine  screw  adjustment  to 

the  optical  part,  with  2  eye-pieces 13  10  0 

No.  3.  A  microscope  stand  without  stage  movements  or  fine-screw  adjustment  with  2 
eye-pieces,  a  one-inch  object-glass  of  15  degrees,  and  a  one-quarter  inch  objectglass 

of  100  degrees — this  is  the  basis  of  a  complete  instrument 14  15  0 

No.  3.  Mechanical  stage  for  ditto 4    00 

No.  3.  Fine  screw  adjustment  for  ditto 2    00 

No.  3.  Sub-stage  and  vertical  rack  motion  for  ditto 4    00 

A  compound  universal  and  tank  microscope  stand,  with  four  rack-and-pinion  adjustments 

and  2  eye-pieces 15    0  0 

A  ditto,  with  binocular  arrangement,  rack-and-pinion  adjustment  to  draw  tubes,  and  two 

pairs  of  eye-pieces 21  12  6 

A  ditto,  ditto,  with  sliding  adjustment  to  draw  tubes,  and  one  pair  of  eye-pieces 19    76 


644 


PEICE-LISTS    OF    MICROSCOPE    FIRMS. 


Microscope    Cases. 

Brass  bound. 

No.  1.  Spanish  mahogany  cabinet  case,  with  box  for  the  apparatus ..  from  £5    50  £7    00 

No.  1.  Portable  mahogany  case fiom    3    00  4    50 

No.  2.  Portable  mahogany  case from    2  10  0  3  15  0 

No.  3.  Portable  mahogany  case from    2    20  3    30 

No.  3.  flat  portable  case from    1  16  0  2  10  0 

No.  3.  Cupboard  case from    1100  2    76 

Achromatic    Object    Glasses    for    Microscopes. 

T.  "Ross  particularly  invites  attention  to  the  great  penetrating  power  and  perfection  of  the  cen- 
tral and  marginal  definition  of  these  objectives.  The  screws  are  cut  to  the  standard  gauge  of  the 
Royal  Microscopical  Society,  and  may  be  applied  to  any  instrument  not  Having  the  Society's  screw 
by  means  of  a!v  adapter  (the  price  of  which  is  2s.  Gd.)  Those  marked  *  have  an  adjustment  for 
covered  and  uncovered  objects. 


OBJECT 

GLASSES. 

Angular 
Aperture. 

Magnifying  powers  with  the 
various  eye-pieces. 

Price. 

Lieber- 
kuhns. 

5  inches. 

7  degs. 

A 

B 

C 

D 

E 

F       i 

£    s.    a. 
1    10    0 

s.    d. 

8 

13 

24 

36 

52 

72 

4        " 

9    " 

10 

16 

30 

45 

65 

90 

1    10    0 

3 

12    " 

13 

•20 

35 

56 

84 

112 

300 

2        " 

15    " 

20 

32 

55 

90 

135 

180 

300 

17  6 

1  1-2  " 

20     " 

25 

40 

70 

112 

168 

224 

300 

17  6 

1        " 

15    " 

37 

60 

105 

170 

255 

340 

200 

15  0 

1 

25    " 

37 

60 

105 

170 

255 

340 

3    10    0 

15  0 

2-3     " 

35    " 

60 

100. 

145 

270 

405 

540 

3    10    0 

10  6 

1.2*   " 

90    " 

95 

153 

265 

420 

630 

840 

550 

10  6 

4-10*  " 

110    " 

140 

220 

370 

650 

975 

1300 

660 

1-4*    " 

100    " 

195 

310 

540 

850 

1275 

1700 

550 

1-4*    " 

140     " 

195 

310 

540 

850 

1275 

1700 

6    10    0 

1-6*    " 

140     " 

320 

510 

700 

910 

1S60 

1820 

770 

1-8*    " 

140     " 

420 

670 

900 

1200 

1800 

2400 

880 

i 

1-12    " 

170     4i 

600 

870 

1200 

2000 

3000 

4000 

12    12    0 

Immersion    Object    Glasses. 

second  anterior  arrangement  may  be  had  with  the  1-8  in.  and  the  1  12  in.  object 
glasses,  which,  when  substituted  for  the  ordinary  front  combinations,  converts  them  into  IMMER- 
SION OBJECTIVES,  giving  most  brilliant  definition.  This  addition,  which  is  strongly  recom- 
mended, thus  enables  the  microscopist  to  use  these  powers  either  with  or  without  water. 

Immersion  arrangement  for  the  1-8  in £2    0  0  extra. 

Immersion  arrangement  for  the  1-12  in 2  10  0     " 

Apparatus    for    Compound    Microscopes. 

£   s.  d. 

"Wenham's  binocular  arrangement,  with  1  eye-piece  and  sliding  adjustment  to  draw  tubes.  550 
Wenham's  binocular  arrangement,   with  3  eye-pieces,   adapter  with  rotating  analyzing 
prism,  combined  rack-and-pinion  adjustment  to  draw  tubes,  and  all  alterations  com- 
plete   8  10  0 

Brooke's  double  nose-piece,  for  rapidly  changing  the  object-glasses 1  10  0 


PKICE-LISTS    OF    MICEOSCOPE    FIRMS.  645 

A,  B  and  C  eye-pieces,  each '. 17  6 

D,  E  and  F  eye-pieces,  each 1    00 

AorB  eye-piece,  with  Slack's  adjustable  diaphragm 1  12  6 

Putting  ditto  to  eye-piece 16  0 

Kelner's  orthoscopic  achromatic  eye-pieces,  giving  double  the  usual  field,  C  and  D,  each. . .  1    40 

Erecting  glasses,  for  dissecting  with  the  compound  microscope 1    00 

Micrometer  eye  -piece 1    4  0 

Screw  micrometer 5    5  0 

Jackson's  micrometer 1    0  0 

Stage  micrometer,  on  slips  of  glass 6  0 

Camera  lucida  (Wollaston's) 1  14  0 

Neutral  tint,  ditto 76 

Condensing  lens,  on  stand £1  and  1  10  0 

Side  condensing  lens 14  0 

Side  reflector,  for  illuminating  opaque  objects 1    50 

Polarizing  apparatus,  with  2  selenites 2  10  0 

Ditto,  with  Barker's  revolving  selenite  stage,  and  set  of  three  selenites,  in  box 4    46 

Ditto,  with  extra  large  polarizing  prism,  additional 1  10  0 

Darker's  revolving  selenite  stage,  and  set  of  three  selenites,  in  box 2    3  6 

Darker's  revolving  selenites,  in  improved  setting,  adapted  to  sub-stage  ;  may  be  used  and 

rotated  either  singly  or  in  combinations  of  two  or  three 3  10  0 

Ditto,  ditto,  with  polarizing  apparatus 5  11  0 

Double  image  prism  and  plate,  for  exhibiting  the  decomposition  of  light,  by  polarization. .  126 

Ross's  achromatic  condenser,  for  transparent  illumination  with  high  and  low  powers 3    00 

Gillett's  achromatic  condenser,  with  series  of  apertures  and  stops  for  illuminating  trans- 
parent objects  and  developing  the  markings  on  diatoms 7    0  0 

New  four-tenths  achromatic  condenser,  with  two  concentric  diaphragm  plates 7  10  0 

Achromatic  condenser,  with  flat  place  of  diaphragms 6    0  0 

Reade's  improved  double  hemispherical  condenser,  with  adjustable  apertures 3  10  0 

Paraboloid  for  dark  ground  illumination 1  13  6 

Spotted  lens  for  ditto  and  for  test  objects 7s.  6d  and      10  6 

Ross's  centring  glass,  for  examining  the  centring  of  the  optical  part  of  microscope 14  0 

Amici's  prism  on  stand,  with  jointed  arms,  for  condensing  an  oblique  pencil  of  light  on 

transparent  objects 2    2  0 

Rainey's  light  modifier 50 

Slack's  ditto 36 

Plate  for  fixing  fish,  frogs,  etc.,  for  exhibiting  the  circulation  of  the  blood 14  0 

Glass  troughs  for  holding  polyps,  etc 4  6 

No.  12. — Price-List  of  Microscopes,  etc.,  of  M.  PILLISCHER,  88  New  Bond 
Street,  London,  W.,  1872. 

Pillischer's   Improved   Microscopes. 

The  construction  of  these  microscopes  is  so  arranged  that  any  form  of  apparatus  can  be  adapted 
without  requiring  the  instrument  for  fitting. 

Prices  of  Stands  only. 

1.  Improved  microscope  stand,  with  coarse  and  fine  adjustments  and  graduated  draw-tube 

(moved  by  rack  and  pinion)  to  the  body,  rack,  and  pinion  stage,  with  one  and  one-quarter 
inch  motions,  in  rectangular  directions,  sliding  and  rotating  object-holder,  and  sliding 
spring  clamp,  secondary  stage  for  holding  and  centring  achromatic  condenser,  polarizing 
and  other  apparatus,  plane  and  concave  mirrors,  revolving  diaphragm,  and  Nos.  1,  2,  3 
eye-pieces £29  0  0 

2.  Improved  smaller  microscope  stand,   with  coarse  and  fine  adjustments  and  graduated 

sliding  draw-tube  to  the  body,  rack  and  pinion  stage,  with  one-inch  motion  in  rectangular 
directions;  sliding  and  rotating  object-holder,  and  sliding  spring  clamp,  secondary  stage, 
with  centring  motions,  plane  and  concave  mirrors,  revolving  diaphragm,  and  Nos.  1, 
2  eye-pieces £14  14  0 

3.  Improved  microscope  stand,  with  coarse  and  fine  adjustments  and  graduated  sliding  draw- 

tube  to  the  body,  rack  and  pinion  stage,  three-quarter  inch  in  rectangular  directions,  slid- 
ing and  rotating  object-holder  and  sliding  spring  clamp,  revolving  diaphragm,  plane  and 
concave  miiTors,  and  Nos.  1,  2  eye-pieces £12  12  0 

4.  Improved  microscope  stand,  with  a  Pillischer's  lever  stage  movement  instead  of  a  rack 

and  pinion,  all  the  rest  the  same  as  above £7  10  0 


646 


PRICE-LISTS    OF    MICROSCOPE    FIRMS. 


Pillisclier's  Improved  Medical  Microscope. 

Inclusive  of  Object  Glasses,  Apparatus,  and  Case,  as  manufactured  for  Her  Majesty's  Army 

Medical  Department. 

5.  Improved  microscope,  with  coarse  and  fine  adjustments  and  graduated  draw-tube  to  the 
body,  rack  and  pinion  stage,  with  three-quarter  inch  motion  in  rectangular  directions, 
sliding  and  rotating  object-holder,  and  sliding  spring  clamp,  plane  and  concave  mirrors, 
revolving  diaphragm,  Nos.  1  and  2  eye-pieces,  one-inch  object  glass,  25  degrees  angular 
aperture,  and  one-quarter  inch  80  degrees,  condenser  for  opaque  objects,  live  box,  and 
upright  mahogany  case,  with  drawer  for  objects,  etc £17  17  0 

Achromatic  Object  Glasses. 


MAGNIFYING  POWER  WITH   THE   VARIOUS 

OBJECT 

ANGULAR 

EYE-PIECES. 

Lieber- 

GLASSES 

APERTURE, 

Price. 

ku.  tin's. 

A. 

B. 

C. 

D. 

£  s.  d. 

4     inch. 

9  degrees. 

10 

16 

30 

35 

1  10  0 

3 

12        " 

14 

22 

37 

60 

1  10  0 

2 

15        " 

20 

35 

60 

90 

2  10  0 

15  6    ' 

2 

12 

u 

u 

" 

•' 

1  10  0 

W 

22        " 

28 

45" 

72 

120 

2  10  0 

15  6 

1 

25 

40 

65 

110 

175 

2  10  0 

14  0 

1 

15 

" 

" 

" 

" 

1  10  0 

X 

80 

95 

155 

270 

430 

500 

,  10  6 

4-10 

55        " 

142 

230 

375 

655 

400 

4-10 

95 

142 

230 

375 

6R5 

500 

K 

100 

195 

310 

540 

850 

500 

K 

80 

n 

H 

" 

3    3  C 

16 

130        ' 

320 

510 

700 

910 

600 

140 

425 

675 

900 

1,200 

7  10  0 

1-20 

150 

950 

1,620 

2,800 

3,500 

15  10  0 

NOTE.— The  object  glasses  are  all  fitted  with  the  Microscopical  Society's  Standard  Screw. 

Prices  of  Apparatus.  £  s.  d. 

6.  Wenham's  binocular  arrangement,  with  rack  and  pinion  adjustment  to  draw-tubes,  and 
one  eye-piece 6    6  6 

7.  Third  eye-piece 0  15  0 

8.  Fourth  ditto 0  17  6 

9.  Improved  achromatic  condenser,  with   series  of  apertures  and   stops  for  illuminating 
objects  of  delicate  structure ^  5    0  0 

10.  Amicis  prism  on  stand,  with  jointed  arms,  for  condensing  an  oblique  pencil  of  light 

£1  10  and  2    20 

11.  Parabolic  condenser,  for  dark  ground  illumination,  with  adjustable  stop 1  10  0 

12.  Large  spotted  lens  for  dark  ground  illumination,  with  low  powers 0  12  6 

13.  Polarizing  apparatus  of  two  Nichol's  prisms  and  selenite 2    2  0 

14.  Tourmalins,  from '. .  0  15  0 

15.  Large  bull's-eye  condenser  on  stand,  with  double  motions 1     26 

16.  Stage  condenser 0  18  0 

17.  Side  reflector  for  illuminating  opaque  objects 1     1  0 

18.  Camera  lucida,  with  prism 0  18  0 

19.  Ditto,          neutral  tinted 0    76 

20.  Compressorium 0  18  0 

21.  Live  box 0    46 

22.  Frog  plate  for  exhibiting  the  circulation  of  the  blood 0    6  6 

23.  Brass  pliers 0    2  6 

24.  Set  of  three  dark  wells  and  holder 0  10  6 

25.  Stage  forceps 0    7  6 

26.  Erecting  eye-piece  for  dissecting  with  the  compound  microscope 0  18  0 

27.  Darker's  selenite  stage 2    2  0 

28.  Brook's  double  nose-piece,  for  rapidly  changing  the  object  glasses 1     7  6 

29.  Double  image  prism,  for  exhibiting  the  decomposition  of  light  by  polarization 1    50 


PKICE-LISTS    OF   MICROSCOPE    FIRMS.  647 

30.  Indicator  to  eye-piece 0    4  6 

31.  Jackson's  micrometer  for  the  eye-piece 0  15  0 

32.  Ditto  ditto         for  the  stage 0    60 

33.  Screw  micrometer : 5    00 

34.  Glass  troughs  for  holding  polypi,  etc 0    40 

35.  Set  of  animalcula  tubes  in  case 0    3  0 

36.  Pocket  spectroscope 1  15  0 

37.  Ditto  ditto        adapted  to  the  microscope,  extra 0  10  0 

38.  Micro-spectroscope,  for  showing  double  spectrum 4100 

Prices  of  Cases  to  Nos.  1,  2,  3  and  4  Microscopes. 

39.  Spanish  mahogany  or  oak  case,  with  two  extra  boxes  for  apparatus,  etc.,  to  No.  1  micro- 
scope   5    00 

40.  Spanish  mahogany  or  walnut  plate-glass  case,  with  four  drawers  for  holding  apparatus, 

etc.,  to  ditto 7    7  0 

41.  Spanish  mahogany  case,  with  two  extra  boxes  for  apparatus,  etc.,  to  No.  2  microscope.  350 

42.  Spanish  mahogany  or  walnut  plate-glass  case,  with  four  drawers  for  apparatus,  etc.,  etc., 

to  ditto ' 6    00 

43.  Spanish  mahogany  case,  with  one  extra  box  for  apparatus,  etc.,  to  No.  3  microscope.   .   2  15  0 

44.  Upright  mahogany  case,  with  drawer  for  objects,  etc.,  to  No.  4  microscope 1  10  0 


Best  Student's   Microscopes. 

Inclusive  of  Object  Glasses,  Apparatus,  and  Case. 

45.  Improved  compound  microscope,  having  coarse  and  fine  adjustments  to  the  body,  a  best 

rack  and  pinion  movable  stage  half-inch  in  rectangular  directions,  concave  and  plane 
mirrors,  and  revolving  diaphragm ;  the  apparatus  supplied  with  this  instrument  consists 
of  Nos.  1  and  2  eye-pieces,  one  inch  and  one-quarter  inch  object  glasses  of  15  and  80 
degrees  angular  aperture,  a  live  box,  stage  forceps,  condenser  for  opaque  objects,  polariz- 
ing apparatus  and  selenite,  and  a  best  made  Spanish  mahogany  or  oak  case,  with  drawer 
for  objects,  etc ' £15  15  0 

46.  Same  size  microscope,  with  a  plain  stage,  or  one  with  Pillischer's  lever  movement,  and  all 

the  rest  the  same  as  above £10  10  0 

47.  The  microscope  stand,  in  every  respect  the  same  as  No.  2,  with  one  eye-piece,  one  inch  and 

one-quarter  inch  object  glasses,  a  condenser  for  opaque  objects,  and  a  plain  mahogany 
case  without  drawer £7  7  0 


Additional  Apparatus. 

Which  can  be  applied  to  Pillischer's  best  Students'  Microscopes. 

48.  Wenham's  binocular  arrangement,  with  rack  and  pinion  adjustment  to  draw-tubes,  and 

one  eye-piece £4  10  0 

49.  Third  eye-piece 0  15  0 

50.  Fourth  ditto       0  17  6 

51.  Bull's-eye  condenser  for  opaque  objects 0    86 

52.  Live  box 0    4  (5 

53.  Stage  forceps 0    5  6 

54.  Polarizing  apparatus  and  selenite 1  100 

55.  Parabolic  reflector  for  dark  ground  illumination 1    50 

56.  Glass  stage  with  cavity 0    10 

57.  Brass  pliers 0    2  0 

58.  Frog  plate  for  exhibiting  the  circulation  of  the  blood 0    5  0 

59.  Spotted  lens  for  dark  ground  illumination  with  low  powers 0  10  6 

60.  Camera  lucida 7s.  6d.  and  0  18  0 

61.  Micrometer  for  the  eye-piece  with  adjusting  screw 0  12  6 

62.  Ditto  for  stage,  divided  into  lOOths  and  lOOOths  of  an  inch 0    60 

63.  Compressorium 0  18  0 

64.  Brook's  double  nose-piece 1    50 

65.  Achromatic  condenser,  simple  form  for  illuminating  objects  of  delicate  structure 2  10  0 

66.  Set  of  dark  wells  and  holders 0  10  0 


648  PKICE-LISTS    OF   MICEOSCOPE    FIEMS. 


No.  13.— Price-List  of  Microscopes  of  C.  BAKER,  243  and  244  High  Hollorn, 
r    London    (1872). 

Achromatic    Microscopes. 

1.  Highly-finished  large  compound  microscope  stand,  with  all  the  latest  improvements, 
having  double  supports  to  prevent  vibration,  vertical  rack  adjustment  for  the  approximate 
focus,  and  fine  screw  motion  for  the  more  delicate  optical  adjustment.  A  mechanical 
stage,  with  one-inch  motion,  in  opposite  directions ;  a  sliding  and  rotating  object  holder, 
a  supplementary  stage,  with  vertical  rack  and  centring  adjustment  for  applying  the 
diaphragm  :  polari  scope,  achromatic  condenser,  spot  lens,  etc  ;  with  plain  and  concave 
mirrors,  and  two  eye-pieces £21  0  0 

1.  A.— A  large  microscope  stand,  with  mechanical  stage,  quick  and  slow  motion,  double 
mirror,  two  eye -pieces,  etc.,  as  above,  but  without  the  supplementary  stage £14  10  0 

1.  B. — A  smaller  ditto,  and  in  every  respect  as  No.  1.  A £11  10    0 

1.  B. — A  ditto,  without  mechanical  stage £7  15    0 

2.  A  smaller  ditto,  with  mechanical  stage,  quick  and  slow  motion,    double  mirror,  and   one 

eye-piece £8  15    0 

2.  A  ditto,  without  mechanical  stage £6  15    0 

Supplementary  stages  applied  to  No.  1  A,  No.  1  B,  or  No.  2 from  £200 

3.  A  superior    finished    binocular  microscope  stand,   with    two  eye-pieces,    double  mirror, 

sliding  stage,  and  quick  and  slow  motions £5  10    0 

Ditto,  ditto,  with  rack  to  eye-pieces  as  above £6    0    0 

Ditto,  ditto,  with  improved  circular  rotating  stage £6  15    0 

The  improved  binocular  arrangement  (Wenham's),  which  allows  the  removal  of  the  prism 
with  its  necessary  fittings,  so  that  when  the  monocular  body  is  used,  an  uninterrupted 

field  Is  obtained.     Applied  to  any  of  the  preceding  microscopes from  £500 

To  students,  or  smaller  instruments from  £3  10    0 

4.  The    student's  microscope,    a  well-finished    instrument,   with    quick  and  slow  motion, 

eliding  and  revolving  stage,  a  combination  of  three  achromatic  powers,  live  box,  stage, 

and  dissecting  forceps,  all  packed  in  neat  mahogany  case £4    4    0 

Ditto,  ditto,  with  superior  rotating  stage,  having  universal  movements .- £4  14    0 

5.  The  educational  microscope.      This  exceedingly  cheap  achromatic  microscope,  which  is 

so  strongly  recommended  by  most  of  the  Professors  at  the  various  Colleges,  Medical 
Schools,  and  Institutions  for  Public  and  Private  Education,  has  quick  and  slow  motion, 
eliding  stage,  live  box,  stage  forceps,  dissecting  ditto,  with  three  achromatic  object  glasses 

in  combination,  all  packed  in  a  neat  mahogany  case £3    3    0 

A  superior-finished  dissecting  microscope,  with  rack  adjustment,  three  object  glasses,  etc.,  in 

neat  mahogany  case £1  15    0 

Achromatic    Object    Glasses. 

Angular  Aperture.        £  s.  d. 

Four-inch 8  degrees 1    5    0 

Three-inch 10  "      115    0 

Two-inch '. 12  "     110    0 

Ditto 15  "     1  17    6 

One-and-a-half-inch 20  "      117    6 

One-inch 15  "     110    0 

Ditto 23  "     117    6 

Ditto 30  "     220 

Two-thirds-inch 35  "      250 

Half-inch,  with  adjustment 60  "      3    0    0 

Ditto,  without 40  "     2  10    0 

Four-tenths,  with  adjustment 70  "     350 

Ditto                          ditto          95  "      310    0 

Quarter-inch,  with  adjustment 75  '•      350 

Ditto                       ditto 95  "     315    0 

Ditto,  without  adjustment ' 75  "      210    0 

One-eighth  ditto,  with  adjustment 115  "      5    5    0 

Ditto                            ditto            125  "      6    6    0 

N.  B.— These  Object  Glasses  are  the  finest  that  can  be  made,  and  for  defining  and  penetrating 
power  cannot  be  surpassed. 


PRICE-LISTS    OF    MICROSCOPE    FIRMS.  649 

A  beautifully-defining  combination  of  German  powers,  half-inch,  dividing  so  as  to  form  one- 
inch  and  one-and-a-half-inch,  mounted  in  a  superior  form ...    £1     2  6 

Ditto,  ditto,  quarter-inch,  and  forming,  if  divided,  one-third-inch 1    5  0 

The  student's  new  English  quarter-inch,  of  70  degrees  aperture 1  10  0 

Lieberkuhns  fitted  to  any  of  the  above  object  glasses from  6s.  to  0  15  0 

The  new  day-light  reflectors  to  ditto 0  15  0 

Ditto,  with  universal  movements  adapted  to  instrument 1    1  0 

Magnifying   Power    of  C.  Baker's  Achromatic  Object    Classes* 

Object  Glasses  With  the  following  Eye-pieces. 

A.  B.  C.               I>. 

Four-inch 10  ....  16  ....  30  ....       45 

Three-inch 17  ....  28  ....  41  ....       50 

Two-inch 25  ....  35  ....  58  ...      70 

One-and-a-half-inch 32  ....  54  ....  75  ....       90 

One-inch 56  ....  76  ....  128  ....  158 

Two-thirds-inch 66  ....  91  ....  132  ....  183 

Half-inch 120  ....  168  ....  280  ....  387 

Four-tenths-inch 172  ....  230  ....  393  ....  480 

Quarter-inch 248  ....  345  ....  575  ....  700 

Quarter-inch 225  ....  312  ....  445  ....  615 

One-eighth-inch 348  ....  558  ...  870  ....1050 

Quarter-inch  German 226  ....  316  ....  453  ....  625 

Half -inch  German 105     147  210     290 

Condensers  for  Opaque  Illumination. 

Large    condenser   for    illuminating    opaque    objects,    with    universal    joint    and  dividing 

stand -  0  15  6 

Ditto,  ditto,  smaller  size,  not  dividing 0  12  6 

Ditto,  ditto,  for  student's  microscopes 0    9  6 

Ditto,  ditto,  for  educational  microscopes 0    7  6 

Achromatic  Condensers   and   Illuminators. 

Gillet's  achromatic  condenser,  with  revolving  diaphragm,  having  complete  sets  of  stops  for 

central  rays,  etc £5    5    0 

The  new  improved  achromatic  condenser,  which  is  also  suitable  for  the  binocular  microscope. 

with  revolving  diaphragm from  £1  10    0 

Parabolic  condenser,  with  central  stops from  £1  5s.  to  1  10    0 

Ditto  ditto,  with  rack  adjustment 1  15    6 

Cloud  condenser  for  binoculars,  fitted  to  stage 0  12    6 

Dark  ground  illuminators  or  spot  lenses,  of  all  kinds from  each  050 

Eeade's  diatom  prism from  050 

Apparatus  for  Achromatic  Microscopes. 

Polariscope,  with  extra  large  pair  of  prisms,  fitted  and  attached  complete £1  12  6 

Ditto,  with  analyzer  expressly  mounted  for  the  binocular  microscope 1  15  0 

Ditto,  with  revolving  analyzer 1  17  6 

Polariscopes  for  student's  or  educational  microscope 1    5  0 

Dr.  Beale's  neutral  tint  glass  reflector  for  drawing 0    5  0 

Brooke's   double    nose-piece,  for    carrying   two    object    glasses  to  facilitate  the  change  of 

focus £1    5  0 

C.  Baker's  triple  ditto,  for  three  object  glasses 1  10  0 

Extra  eye-pieces from  6s.  to     0  12  6 

Kelner's  orthoscopic  achromatic  eye-piece,  giving  a  very  large  field 1    0  0 

Revolving  selenite  stages,  with  complete  sets  of  selenites 2    0  0 

Erecting  glasses  for  dissecting,  applied  to  draw  tubes 0  15  0 

Camera  lucida,  for  drawing  the  magnified  image .from  15s.  to     1    0  0 

Stage  forceps from  3s.  6d.  to     056 

Dissecting  forceps Is.  to     019 

Micrometer  for  stage 0    4  6 

Ditto,  for  eye-piece,  mounted  in  brass 0    8  6 

Ditto  ditto,  immounted 0    6  0 


650 


PRICE-LISTS    OF    MICKOSCOPE    FIEMS. 


No.  14. — Price-List  of  the  Microscopes  and  Microscopic  Apparatus  of  CHAS. 
A.  SPENCER  &  SONS,  Canaslota,  N.  Y.  (1872). 

Price  in  Dollars. 

Student's  Microscope,  No.  1.  Height,  15  inches  ;  weight,  6  Ibs.  The  arm,  pillar,  and  base  are 
of  japanned  iron ;  arm  attached  by  cradle-joint,  and  taking  any  position  from  vertical  to 
horizontal ;  coarse  adjustment  by  sliding  tube  in  velveted  clip,  and  the  fine  by  milled  head 
upon  the  stage ;  by  a  curved  arm  the  double  mirror  (plane  and  concave)  has  u  lateral 
movement  for  oblique  light,  or  may  be  swung  above  the  stage  for  side  illumination  of 
opaque  objects.  It  is  furnished  with  B  eye-piece ;  1  in.  objective  of  20°  angle  of  aperture, 
with  a  very  flat  and  well-defined  field,  giving  a  power  of  85  diametejs  ;  a  ^  in.  of  60°  angle 
of  aperture,  adjustable  by  front  lens,  giving  a  power  of  325  diam.  In  neat  cabinet $60  00 

Student's  Microscope,  Stand  No.  2.  Like  No.  1,  with  addition  of  rack  and  pinion  for  coarse 
adjustment,  and  micrometer  screw  and  lever  fine  adjustment  to  nose-piece ;  camera  lucida, 
and  animalcule  cage ;  same  objectives,  eye-piece  and  cabinet $100  00 

Student's  Microscope,  Stand  No.  3J  Stand  of  finished  bronze  and  brass ;  complete  as  in  No.  2 ; 
A  and  B  eye-pieces;  2  in.  objective  of  12°  ang.  ap. ;  1  in.  objective  of  20°  ang.  ap. ;  %  in. 
of  60°  ;  camera  lucida ;  cabinet $125  OC 

Student's  Microscope.    Stand  like  No.  3 ;  in  cabinet ;  B  eye-piece ;  1  in.  objective  of  20°  ang.  ap. : 

1-5  in.  100°  ang.  ap.,  adjustable  for  cover $125  00 

Student's  Microscope.  Stand  like  No.  3 ;  with  A  and  B  eye-pieces,  and  %  in.  objective  of  60°  ; 
cabinet $105  00 

Standard  Microscope,  No.  1.  Stand  17  inches  high ;  weight,  11  Ibs.  This  mounting,  of  the 
simplest  and  cheapest  form,  has  the  arm,  pillar,  and  base  of  finished  japanned  iron ;  the 
arm  attached  by  cradle  joint  and  taking  any  position  from  vertical  to  horizontal ;  the  coarse 
adjustment  by  rack  and  pinion,  or  by  new  friction  pinion ;  the  mirror  (plane  and  concave) 
adjustable  for  oblique  light  or  for  side  illumination  of  opaque  objects ;  packed  in  cabinet  $75  00 

The  friction  movement  mentioned  is  new  in  arrangement,  and  so  perfect  in  action  as  to  render 
a  fine  adjustment  unnecessary  for  most  observers  ;  it  can  be  changed  almost  instantly, 
from  giving  a  light  free  motion  to  one  so  tense  as  almost  to  lock  the  main  tube.  When 
required,  however,  a  fine  adjustment  is  added  at  a  cost  of  $10  additional,  or $85  00 

Standard  Microscope,  same  as  No.  1,  with  addition  of  fine  adjustment;  graduated  draw-tube  ; 
sub-stage  for  accessories,  movable  with  rack  and  pinion,  and  with  screws  for  centring ; 
cabinet $125  00 

Same  mounting,  complete  as  last  mentioned,  of  finished  brass  and  bronze $150  00 

Other  forms  and  sizes  of  stands  made  to  order. 


First-class  Objectives.     L.arge  Angles  of  Aperture. 


FOCAL  LENOTH. 

ANG.  OF  AP. 

Price 

I 

FOCAL  LENGTH 

ANG.  OF  AP. 

Price. 

4  in.  adjustable  to  3  in. 
2            inch. 

27° 

$35 
30 

1-4            inch. 
1-4 

160° 

170°  to  175°  new  form 

$65     o 
7ol   "* 

Itf 
1                "  

37° 
30° 

30 
30 

1-8 
1-12 

175° 
175°              " 

80     2 
100     £ 

1                " 

40°  to  45° 

40 

1-15  or  1-16 

175°              " 

120  |  B 

1-2            "  . 

80° 

40 

1-20 

175°              '• 

150     3 

4-10          " 

90° 

45 

1-50 

175°              " 

200     % 

1-4  or  1-5  "  

140° 

50  | 

First-class  Objectives.     Medium  and  Smaller  Angles  of  Aperture. 


FOCAL  LENGTH. 

ANG.  OF  AP. 

Price 

1 

FOCAL  LENGTH 

ANG.  OF  AP. 

Price. 

2  inch 

12° 

$15 

80° 

$35 

1     '•     ..  

X  " 

20° 
55°  to  60° 

20 
35 

1-4 

:l-5  or  1-6     " 

60°  adjst.byfr. 
100°              [lens 

25 
40 

X  "    

40°  non-adjst. 

20 

i142       " 

140° 

70 

Objectives  are  made  with  L.  M.  Society's  screw,  or  our  standard  bayonet  catch,  as  may  be 
ordered. 


PRICE-LISTS    OF    MICROSCOPE    FIRMS. 


651 


No.  15. — Price- List  of  Microscopes  and  Microscopic  Apparatus  of  J '.  GTRUNOW, 
410  Fourth  Avenue,  N.  Y.  (1872). 

Student's  Microscope.  Horse-shoe  brass  base ;  12  inches  high,  weighs  5  Ibs.  :  coarse  adjust- 
ment by  sliding  tube,  fine  by  screw  to  compound  body ;  plain  stage  with  spring  clips ; 
diaphragm  sunk  into  upper  surface  of  stage,  so  as  to  be  close  to  the  object  slide ;  plane  and 
concave  mirror,  with  hinge-movement ;  two  eye-pieces :  objectives  %  in.  of  25°  angle  of 
aperture,  and  1-5  in.  90°  ang.  ap.  ;  giving  a  power  of  70-500  diameters.  In  case $85  Ou 

Student's  Microscope,  same  as  above,  with  camera  lucida,  stage  micrometer,  and  compres- 
sorium $100  00 

First-class  Acliromatfc   Objectives. 

4       in.  12    degrees  angular  aperture $18  00 

3       in.             12          "                         "          1800 

2       in.              20          "                         "          18  00 

1^  in.              2-2          "                         "          1800 

1       in.             25-20     "                         "          2000 

2-3    in.             ?5          "                         "            ... .' 2200 

4-10  in.             75          "                         "          2500 

4-10  in.            1(10-110"                         "          ?5  00 

1-5    in.            110           '                         "          (.5  00 

1-5   in.            135-140    '                         "          4000 

1-8    in.            140-150    '                         "          4500 

1-10  in.            1(50           '                         "          5000 

1-15  in.           100           '                 _       "          75  00 

The  1-10  in.  and  1-15  in.  are  immersion  objectives. 

Objectives  for  Student's  Microscopes. 

In  neat  morocco  cases,  the  same  as  the  Objectives  of  Nachet,  Hartnack,  and  others. 

1 X  in.  15    degrees  angular  aperture , $12  00 

2-3    in.              25          "            "            "          1500 

4-10  in.              50          "            "            "          1800 

1-5    in.              90          "            "            "          2000 

1-10  in.            130  (immersion)             "          80  00 

Accessories  for  the  Microscope. 

Achromatic  condenser $35  00 

Polariscope  "        $25-30  00 

Camera  lucida 6  00 

"       best  (invented  by  J.  Grunow) 15  00 

Erector     "  700 

Extra  eye-pieces    " 600 

Orthoscopic  or  Kellner  eye-piece 10  00 

Amicis'  prism  "         1200 

Eye-piece  micrometer 5  CO 

Microscope  Stands,  of  the  best  American  make,  are  furnished  to  order,  at  manufacturers'  prices. 


No.  16. — Price- List  of  Microscopes   and  Microscopic   Apparatus  of  R.   B- 
TOLLES  (CHARLES  STODDER,  Agent),  66  Milk  Street,  Boston,  Mass.  (1872). 

Student's  Microscope.  15  inches  high  ;  weight,  6  Ibs. ;  .the  base,  uprights,  and  curved  arm  are 
of  iron  handsomely  japanned :  on  a  trunnion  joint,  made  on  a  new  plan  to  wear  well,  by 
which  the  instrument  can  be  inclined  from  vertical  to  horizontal,  with  a  stop  to  prevent 
movement  beyond  these  points.  It  is  furnished  with  a  B  eye-piece,  two  second-quality 
objectives,  1  in.  and  %  in.  focus ;  giving  about  60  and  280  diameters ;  a  plain  stage  with 
spring  clips  for  holding  slides ;  revolving  diaphragm ;  concave  mirror,  with  movement  to 
give  oblique  light ;  for  illumination  of  opaque  objects  mirror  is  removed  to  an  upright 
staml ;  coarse  adjustment  by  sliding  compound  body,  which  is  held  in  place  by  a  steel 
spring  ;  fine,  by  a  new  construction  efficient  with  high  powers.  Upright  black  walnut 
or  mahogany  case $70  00 

The  same,  with  fine  adjustment  on  stage $50  00 

Additions.— Extra  eye-pieces  A  and  C,  $4  each  ;  a  superior  camera  lucida,  $5;  sub-stage 
for  accessory  apparatus,  $5  ;  sliding  stage  giving  vertical  and  horizontal  motions  by  the 
hand,  and  adapted  for  the  use  of  Maltwood  finder.  $15  ;  rack  and  pinion  for  coarse  adjust- 
ment, $12  ;  stand,  all  brass,  $10. 

Large  Microscope  B.  This  instrument  is  intended  to  meet  the  wants  of  the  scientific  investi- 
gator :  to  attain  everything  that  the  mtcroscopist  can  accomplish,  without  sparing  the 
cost,  and  to  permit  the  use  of  all  the  modern  accessory  apparatus ;  constructed  on  the 
curved  arm  (Jackson)  model;  18  inches  high,  weighs  about  14  Ibs. ;  the  curved  arm  is 
supported  on  a  steel  trunnion  between  two  strong  brass  pillars,  made  for  durability  and 


652  PEICE-LISTS    OF   MICEOSCOPE    FIKMS. 

not  liable  to  get  out  of  order,  and  provided  with  a  method  of  compensation  for  wear  ;  has 
rack  and  pinion  for  coarse,  and  micrometer  screw  for  fine  adjustment  of  focus ;  graduated 
draw-tube ;  sub-stage,  with  rack  and  pinion,  and  centring  screwg  for  accessory  apparatus ; 
plane  and  concave  mirrors  on  double- jointed  arm  ;  Tolle's  thin  stage,  admitting  light  of 
great  obliquity,  with  rectangular  movements  by  screw,  and  rack  and  pinion  ;  rotation  on 

the  optical  axis  of  about  270°  ;  all  that  is  practically  necessary $225  00 

A  modification  of  this  size,  with  the  stage  carried  by  friction  rollers,  and  entire  rotation  on  the 

optical  axis,  can  be  made $275  00 

Largest  Microscope  A.  This  instrument  is  one  of  the  largest  yet  produced  anywhere.  It  is 
similar  in  all  respects  of  style  and  construction  to  the  B  instrument,  but  larger  and 
heavier,  weighing  20  Ibs.  The  stage  is  six  inches  in  diameter,  and  makes  fi  complete 
revolution  on  the  optical  axis.  The  whole  instrument  rotates  on  a  stout  plate  graduated 

to  degrees.     Price  of  stand $300  00 

Can  be  furnished  with  radial  arm  to  carry  accessory  apparatus  at  any  angle,  for $50  00 

Pocket  microscope,  for  clinical  and  field  or  sea-side  use ;  is  a  simple  tube  6  in.  long,  %-in, 
objective  ;  B  eye-piece  ;  fine  and  coarse  adjustments  ;  stage  with  spring  clips  to  hold  the 
object,  which  can  be  removed  when  not  in  use.  and  the  objective  covered  with  a  brass 

cap $25  00 

With  draw  tube  for  increasing  the  power 30  00 

As  the  same  eye-pieces  and  objectives  are  used  for  the  student's  microscope,  those  who  want 
both  instruments  require  but  one  set  of  the  optical  parts. 

Accessories. 

Huyghen's  negative  eye-piece  2-in.  $10,  1^-in.  $9,  1-in.  $8,  %-in.  $7 

Ditto,  ?'       for  student's  microscopes $4  each. 

Tolles1  patent  solid  eye-pieces %-in.  $8,  &-in.  $8,  %-in.  $7 

Tolles'  solid  orthoscopic  eye-pieces  (this  eye-piece  makes  an  excellent  achromatic  condenser), 

1-in.  $15,  %-in.  and  higher  powers $12  00 

Tolles'  binocular  eye-piece 80  00 

Tolles'  amplifier,  to  double  the  power  of  any  specified  objective  and  eye-piece,  without  disturb- 
ing the  "corrections," $12  00 

Higher  power  amplifiers  by  special  arrangement. 

Tolles'  achromatic  triplets  for  the  pocket,  in  silver  cases,  jkf-in.  and  %-in.  $12,  %-m.  $14,  %- 

in.  extra  large  mounting $14  00 

1-inch  do.  do.  with  610-inch  field $16  00 

Double  nose-piece $8  to  $12  00 

Camera  lucida $5  00 

Objectives. 

First  quality  of  large  angular  aperture.  These  are  made  for  the  highest  requirements  of  the 
microscopist  and  histologist,  as  tracing  nerve  fibre,  cell  formation,  resolution  of  Nobert's 
lines,  etc.,  etc. 

1-2  inch  ang.   ap  60°  to    80° $40  00 

4-10      "        "      "  90°  to  110° 4500 

4-10      "        "      "          135°  to  145° 6500 

This  objective  may  be  used  as  an  achromatic  condenser,  with  special  advantage. 

1-4  &1-5  inch   ang.   ap.          110°   to  130° $50  00 

1-4      "        "      "  up    to    150° 6000 

1-4     "        "      "  "     "170° 7000 

1-6      ' '     $5  advance  on  l-4th. 

1-8      "    ang.  ap.    under  140° $65  00 

1-8      "      "       "        to      100° 7500 

1-8     "      "       "        to      175° 8000 

1-10      "     $5  advance  on  price  of  l-8th. 

1-12      "    ang.  ap.      under  140° $8000 

1-12      li      "        "      up  to  160° 10000 

1-12      '•      "        "        "  to  175° 11500 

1-15      "       "        "        "  to  160° 12000 

1-15      "      "        "        "  to  175° 12500 

1-20      "      "       «•  .     "  to  175° ...18000 


PRICE-LISTS    OF    MICROSCOPE    FIRMS.  653 

First  quality  objectives  of  lower  angular  aperture  having  properly  more  penetration  and  better 

adapted  for  some  anatomical  and  botanical  investigations. 
1-2  inch  ang.   ap.  60°  or  less  ...................................................  $35  00 

4-10     "        "        "  85°"     "    .................................................  4000 

1-4&15"        "        "  100°    "     "    ...................................................  4000 

1-6    "       "       "  100°    "     "    ..................................................  4500 

1.8     "        "        "  1UO°    "     "    ...................................................  4500 

1-10     "        "        "  100°"     "     ...................................................  4500 

1-12     "        "        "  120°    kt     "    ...................................................  6000 

1-15     "       "       "  100°"     'k    ...................................................  7000 

1.20     "       «       »  100°"    "    .................................................  10000 

All  of  l-5th  inch  or  higher  powers  will  be  made  either  dry  or  immersion  at  the  same  price  ;  to 
work  both  ways  with  the  same  lens,  from  $5  to  $15  extra.     With  an  extra  "front"  lens 
$10  to  2-5ths  extra.    All  the  foregoing  have  Tolles'  adjustment  for  covering  glass,  which 
does  not  move  the  front  lens. 

First  quality  objectives,  without  adjustment  for  cover. 
4-inch,  adjustable  to  3-inch  .............................................  ................  $35  00 

4-inch,  changeable  to  2>£-inch  ...........................................................  18  00 

2-inch  ........................  .  ..........................................................  20  00 

2-inch,  higher  ang.  ap  ......  .'  ...........................................................  23  00 

l^-inch  and  1-inch,  in  one  ...............................................................  28  00 

1-inch  17°  ...............................................................................  20  00 

1-inch  25°  ....................................................................  ..........  23  00 

1-inch  SO0  ..............  .................................................................  30  00 

%-inch,  new  formula,  specially  flat-field  ..................................................  30  00 

X-inch  25°  to  40°  .......................................................................  23  00 

>£-inch,  specially  constructed  for  viewing  opaque  objects  ........................  '.  .........  28  00 

j^-inch,  40°  to  70°,  adjusting  by  front  lens  ...............................................  26  00 

&-incb,  to  70°  "          "      "        "    ...............................................  3500 

Second  quality  objectives  ...............  1-inch  and  2-mch  $8,  1-2-inch  $10,  1-4  and  1-6  $15  to  $20 

All  objectives  are  made  with  ttie  "  Society"  screw,  so  as  to  fit  all  recent  English  or  American 
stands  —  unie&s  ordered  otherwise. 

No.    17.  —  Price-List  of  Microscopes  and  Microscopic  Accessories  of  J.  ZLNT- 
MAYER,  147  South  ±th  Street,  Philadelphia,  Pa.  (1872). 

1.  TJ.  S.  army  hospital  microscope,  brass  body,  16  inches  high,  on  brass  stand,  with  joint  to 
incline  it  to  any  angle,  double-milled  head,  rack  and  pinion  for  coarse  adjustment,  mi- 
crometer screw  for  fine  adjustment,  movable  glass  stage  ;  under  the  stage  a  tube  is  fitted 
for  carrying  the  accessory  illuminating  apparatus  ;  concave  and  plane  mirrors,  arranged 
for  direct  or  oblique  illumination  ;  draw  tube  for  increasing  the  power  ;  two  eye-pieces  ; 
one  achromatic  object  glass,  ^  of  an  inch  focus  of  32  degrees  angular  aperture  ;  one 
achromatic  object  glass,  -4-  of  an  inch  focus  of  80  degrees  angular  aperture  (not  adjustable 
for  glass  cover),  giving  power  of  50,  100,  250  and  450  diameters  ;  camera  lucida,  stage  my 
crometer  ruled  J-  and  ---  of  an  inch,  and  a  condensing  lens  two  inches  diameter  on 


separate  stand.     Securely  packed  in  a  neat  walnut  box  with  lock  and  key  ............  $135  00 

2.  Grand  American  microscope.  The  most  complete  and  perfect  instrument  of  the  kind  now 
made.  It  ia  19  inches  high  on  tripod  base.  The  two  brass  pillars  upon  which  the  body 
and  stage  are  swung  rest  upon  a  revolving  plate  with  graduated  edge,  by  which  the  angu- 
lar aperture  of  the  object  glasses  can  be  ascertained  ;  the  body  is  moved  with  a  double- 
milled  head  ;  pinion  and  rack  for  the  coarse  adjustment,  and  a  fine  micrometer  screw  for 
the  delicate  adjustment.  The  mechanical  stage  has  a  screw  adjustment  with  milled  head 
for  the  horizontal  motion,  and  a  delicate  chain  and  pinion  with  milled  head  for  the  verti- 
cal motion.  On  the  centre  of  the  tipper  side  of  the  stage  a  circular  plate  with  graduated 
edge  is  attached  for  measuring  angles  of  crystals  ;  the  whole  thickness  of  the  stage  is  but 
ji.  of  an  inch,  but  at  the  same  time  perfectly  solid  and  steady,  and  affording  unusual  fa- 
cility for  great  obliquity  of  illumination  when  difficult  tests  are  to  'be  resolved.  Under 
the  stage  a  small  tube  with  rack  and  pinion  is  attached  ;  in  this  tube  the  accessory  illumi- 
nating apparatus  is  carried  when  in  use.  The  mirror  has  one  side  plane  and  the  other 
concave  ;  the  bar  which  carries  it  is  jointed,  to  give  the  required  motion  for  oblique  illu- 
mination. There  is  a  graduated  draw  tube  sliding  into  the  main  tube  of  the  body  for 
increasing  the  magnifying  power,  by  lengthening  the  distance  between  the  object  glass 
and  eye-piece.  Three  eye-pieces  ;  one  achromatic  object  glass,  1>£  inch  focus,  2'J  degrees 
angle  of  aperture,  and  one  achromatic  object  glass  •*  of  an  inch  focus,  80  degrees  angle 
of  aperture  ;  power  50-500  diameters  ;  large  condensing  lens  on  separate  stand.  All 
packed  in  a  handsome  walnut  cabinet,  with  lock  and  key  ............................  $262  00 


654  PRICE-LISTS    OF    MICROSCOPE    FIRMS. 

No.  3.  Grand  American  microscope,  the  same  as  No.  2,  but  with  the  following  accessories  :— 
3  eye-pieces;  achromatic  object-glass,  1%  inch  focus,  22  degrees  angle  of  aperture; 
1  achromatic  object-glass,  8-1U  of  an  inch  focus,  32  degrees  angle  of  apeiture;  1  achro- 
matic object-glass,  4-10  of  an  inch  focus,  8U  degrees  ang.e  of  apeiture,  witli  adj ustinent  f or 
thin  glass  cover ;  1  achromatic  object-glass,  1-5  of  an  inch  focus,  120  degiees  angle  of 
aperture,  with  adjustment  for  tuiu  glass  cover;  polarizing  apparatus  with  seleiiite  plate, 
parabola  for  dark  field  illumination,  erector,  large  condensing  lens  on  separate  stand, 
camera  lucida,  stage  micrometer  ruled  to  1-lUUth  and  1-lUtOth  of  an  inch,  stage  forceps, 
animalcule  cage,  zoophyte  trough,  blue  glass  cap.  The  whole  packed  in  a  highly  polished 

matiogany  cabinet $400  00 

No.  4.  Grand  American  microscope.     Stand  only,  same  as  No.  2,  with  three  eye- pieces.    No 

object-glasses,  no  box §>~00  00 

No.  5.  Student's  microscope,  brass  stand  and  body,  bronzed,  16  inches  high,  with  joint  to 
incline  to  any  angle ;  micrometer  screw  for  tine  adjustment ;  broad  stage  with  clips  for 
holding  the  object;  under  the  stage  a  tube  is  fitted  for  carrying  the  accessory  illuminating 
apparatus;  concave  and  plane  mirrors,  ai ranged  for  direct  or  oblique  illumination  ;  two 
eye-pieces ;  1  achromatic  object-glass,  8-10  of  an  inch  focus,  24  degrees  angular  aperture  ; 
1  achromatic  object-glass,  1-5  of  an  inch  focus,  80  degrees  angular  apeiture  (not  adjustable 
for  glass  cover),  giving  power  of  50,  100,  250  and  450  diameters,  and  a  condensing  lens 

attached  to  the  stand.     Securely  packed  in  a  neat  walnut  box,  with  lock  and  key $15  00 

No.  6.  Clinical  microscope.  This  instrument  is  especially  arranged  tor  class  demonstration, 
and  is  an  elaboration  of,  and  improvement  upon  the  class  micioscope  of  i)r.  Beale.  It 
consists  of  full-size  body  w^th  draw-tube  ;  coarse  and  fine  adjustments  of  focus  ;  2  eye- 
pieces ;  1  achromatic  object-glass,  8-10  of  an  inch  focus,  24  degrees  angular  aperture ; 
1  achromatic  object-glass,  1-5  of  ail  inch  focus,  80  degrees  angular  aperture  (not  adjustable 
for  glass  cover),  giving  powers  from  50-45U  diam.  ;  lamp  for  direct  illumination,  arranged 
upon  a  sliding  bar.  ami  giving  every  facility  for  the  accurate  examination  of  any  object  by 
a  large  class,  by  being  passed  from  hand  to  hand.  The  whole  enclosed  in  a  neat  and  very 

portable  oiled  walnut  case $60  00 

Achromatic  condenser,  with  centring  adjustment,   revolving  diaphragm  plate,    achromatic 

combination  of  X  aiKl  1-5  in $38  00 

Polarizing  apparatus $25 — 55  00 

Selenite  plate 1  00 

1'arabolic  illuminator,  mounted, 14  00 

Achromatic  oblique  prism,  mounted 14  UO 

Amici's  prism,  mounted 10  00 

Erector,  mounted 6  00 

liuli's-eye  condenser,  3  inches  diameter,  on  stand 10  00 

Camera  lucida,  mounted 8  00 

Stage  micrometer,  divided  1-100  and  1-1000  of  an  inch 2  00 

do.          do.  do.      1  100,  1-1000.  and  1-2000  of  an  inch 2  50 

Eye  piece  micrometer,  with  micrometer  screw 6  00 

Stage  forceps 4  00 

Animalcule  cage 3  50 

Zoophyte  trough 3  00 

Blue  glass  cap,  to  place  under  the  stage  to  modify  the  light 1  50 

Eye-pieces,  each 6  GO 

Mechanical  finger 20  00 

4  and  5  in.  objective  combined,  a  very  low  power  to  overlook  a  large  slide  at  once 15  00 

3  and  4  in.  objective  combined 15  00 

in.  objective.        Ang.  ap.    22° 15  00 

bO° 18  00 


8-10 
4-10  in. 
1-5  in. 
8-10  in. 
1-5  in. 


65°  (adjustable) 25  CO 

120°.... 3500 

24° 12  00 

85°  ...  18  00 


No.  18,—Price-Listof  Objectives  made  by  WM.  WALES,  Fort  Lee,  N.J.  (1872;. 

4       in.  Angle  aperture    -9° , $1200 

3       in.  '•  "          12° 1500 

IX    in.  "  "          23° 1700 

2-3    in.  "  "          30° 2000 

4-10  in.  "  "          75° 4000 

4-10  in.  "  "          9U° 40  00 

4.10  in.  "  "        110° 40  00 

1-4    in.  "  "          90° 30  00 

1-5    in.  '         135° 40  00 

1-5    in.  '         165°  (immersion) 50  00 

1-8    in.  '         145° 4500 

1-10  in.  '         160°  (immersion) 50  00 

1-15  in.  "  '         170°          "            7500 

1-30  in.  '         160°          "                                   120  00 


PRICE-LISTS    OF    MICROSCOPE    FIRMS. 


655 


No.  19. — Price-List  of  Microscopes  and  Accessories  of  MILLER  BROTHERS, 
69  Nassau  Street,  and  1223  Broadway,  New  York  (1872). 

Price  in  Dollars. 

Microscope  stand  A.  This  binocular  microscope  is  of  first-class  quality  in  every  respect.  The 
stand  is  firm  and  free  from  tremor  under  observation,  even  while  the  adjustment  of  appa- 
ratus is  going  on.  The  binocular  mechanism  is  very  superior,  realizing  both  the  stereo- 
scopic and  perspective  views  of  the  object  with  remarkable  ease  and  perfection.  In  addi- 
tion to  a  rectangular  motion  of  one  inch  in  each  direction,  and  rotation  by  hand,  the  whole 
stage  rotates  concentrically  and  independently  by  means  of  a  rack  and  pinion  on  a  circu- 
lar plate,  graduated  so  as  to  form  a  goniometer  or  position  micrometer.  The  secondary 
or  sub-stage  has  adjusting  screws  for  centring  all  the  supplementary  apparatus  which  it 
receives,  and  affords  facilities  for  the  manipulation  and  use  in  the  most  convenient  and 
efficient  manner,  possessing  also  the  means  of  rotation  by  rack  and  pinion,  with  graduated 
divisions  at  the  circumference.  Fine  adjustment  of  the  most  delicate  and  perfect  construc- 
tion ,  the  index  reading  off  differences  in  the  focal  position  of  the  objective  to  the  5-1000 
of  an  inch,  perceptible  co  the  observer's  eye.  Including  4  eye-pieces .'. . $275  00 

If  with  single  body,  2  eye-pieces $230  00 

Microscope  stand  B.  Constructed  on  the  same  general  plan  as  A,  but  smaller.  Stage  has 
usual  rectangular  motion,  and  one  of  rotation,  without  rack  and  pinion.  Sub-stage  has  a 
rotating  cylinder,  with  adjustments  for  centring  the  apparatus  which  it  receives,  and 
provides  for  their  use  and  application  with  freedom.  Flat  and  concave  mirror  on  double 
arm.  Binocular,  with  4  eye-piece.s $220 

Single  body.  2  eye-pieces '.e"~  00 

Microscope  stand  C ;  rather  smaller  than  B,  stage  is  remarkably  thin,  has  a  rotating  object 
plate,  and  a  rectangular  motion  of  %-ineh,  both  in  vertical  and  horizontal  directions. 
Polarizer  and  sub-stage  appliances  are  fixed  by  means  of  a  sliding  dovetail  plate,  with  a 
stop  to  insure  their  concentric  position  when  in  use  ;  with  two  eye-pieces $135  00 

If  binocular,  with  four  eye-pieces 180  00 

Microscope  stand  D ;  formed  on  same  general  design  as  B,  but  smaller ;  has  a  rack  and 
pinion,  and  a  fine  adjustment ;  rectangular  screw  and  rack  motion  to  stage  ;  rotary  dia- 
phragm ;  two  Huyghenian  eye-pieces  A  and  B  ;  concave  and  flat  mirror $70  00 

If  binocular,  four  eye-pieces,  rack  and  pinion $100  00 

New  educational  microscope  E  (stand  entirely  of  brass),  has  a  fine  adjustment,  and  the  fol- 
lowing accessories  fitted  with  it  in  a  polished  mahogany  case :  Two  Huyghenian  eye- 
pieces A  and  B  :  1-inch  objective,  16°  angular  aperture ;  3^-inch  objective,  75°  angular 
aperture ;  condensing  lens  on  separate  stand ;  pair  of  pliers ;  four  stage  plates  and 
cells $80  00 

Student's  microscope,  16  inches  high,  weighs  5  pounds  ;  base  upright  and  curved  arm  of  iron 
handsomely  japanned  ;  trunnion  joint,  made  on  a  new.plan  to  wear  well,  by  which  the 
instrument  can  be  inclined  from  vertical  to  horizontal,  with  stop  to  prevent  movement 
beyond  these  points.  Is  furnished  with  A  and  B  eye-pieces,  a  good  achromatic  objective, 
>£-inch,  with  magnifying  power  of  153  diameters ;  plain  stage ;  spring  clasp  for  holding 
slides ;  concave  mirror,  with  movement  for  oblique  light,  removed  to  stage  for  opaque  ob- 
jects ;  coarse  adjustment  by  sliding  tube  through  cloth  packing,  fine  by  a  new  construc- 
tion efficient  with  high  powers $35  00 

With  case 40  CO 

First-Class    Achromatic    Objectives. 


Focal 
•     Length. 

Angular 
Aperture 

Linear  Magnifying  Power  with 
the  respective  Eye-pieces. 

Price. 

Lieberkuhn's 
Reflectors, 
Extra. 

A. 

B. 

C.      | 

D. 

Inches. 
3 
2 

1 
1*6 

Degrees. 
12 
15 
20 
25 
30 
75 
100 
130 
140 

13 

20 
25 
37 
60 
95 
195 
320 
420 

20 
32 
40 
60 
100 
153 
310 
510 
670 

35 
55 

70 
105 
145 
265 
540 
700 
900 

56 
90 
112 
170 
270 
420 
850 
910 
1200 

$18.00 
18.00 

22.00 
22.00 
22.00 
36.00 
41).  00 
54.00 
72.00 

$8.00 
7.00 
7.00 
5.50 
"    4.50 

All  powers  higher  than  two-thirds  have  the  adjustment  for  covered  and  uncovered  objects. 


656 


PRICE-LISTS    OF    MICROSCOPE    FIRMS. 


Achromatic    Objectives   with    less    Angular    Aperture, 


3 

10 

13 

20 

35 

56 

$13.50 

None  of  these 

2 

12 

20 

'6-2 

55 

90 

13.50 

have    the  ad- 

1 

16 

'61 

60 

106 

170 

13.50 

justment    for 

X 

55 

95 

153 

265 

420 

18.00 

covered     and 

% 

7U 

196 

310 

540 

85J 

18.00 

uncovered  ob- 

H 

80 

195 

3iO 

54U 

850 

27.00 

jects. 

All  the  objectives  constructed  by  Miller  Brothers  are   made  with  the  Royal  Microscopical  Society's 

Universal  Screw. 

Microscopical    Apparatus,  Et«. 

Extra  eye-pieces,  A,  B,  C  and  D each,  $  5  00 

Erecting  eye-piece  for  dissecting 9  00 

Improved  micrometer  eye-piece 10  00 

Reiner's  orthoscopic  eye-piece,  C  or  D,  double-size  field 10  00 

Sorby's  spectroscope  $30  00  to  50  00 

Bull's-eye  condenser,  on  stand $3  50,  and  5,  6,  7,  8  9  00 

Webster's  achromatic  condenser $15  00  and  40  00 

Hall's  universal  condenser  and  appliances $27  00  to  45  00 

Gillet's  achromatic  condenser,  with  latest  improvements 60  00 

Eye-piece  for  centring  do 5  00 

Plain  achromatic  condenser,  with  }£-inch  objective,  central  and  annular  stops 20  00 

Read's  hemispherical  or  kettle-drum  condenser 13  50 

Set  of  Rainey's  light  modifiers 4  00 

Camera  lucida,  Wollaston's $8  00  and  10  GO 

Do.        do.        neutral  tint  glass 3  00 

Polarizing  apparatus $20  00  and  25  00 

Selenites,  selected  colors,  $1  00  each ;  best,  brass  mounted 2  25 

Set  of  Barker's  do.,  revolving,  brass  mounted 20  00 

Barker's  new  series  of  3  selenites.  to  rotate  either  singly  or  combined,  showing  13  colors  and 

complementary  tints 31  00 

Lister's  set  dark  wells 5  00 

Dark  field  condenser,  with  adjustment 4  00  to  5  00 

Wenham's  parabolic  reflector $9  50 ;  best  14  00 

Silver  side  reflector,  for  opaque  objects 9  50 

Silver  parbolic  stage  reflector 9  50 

Beck's  illuminator,  for  opaque  objects  under  high  power 4  00 

Amici's  prism,  for  oblique  illumination 20  00 

Nachet's   do.  do.  do.  9  50 

Rectangular  do.,  reflection  of  parallel  rays 18  00 

Brooke's  arm,  for  two  objectives 10  00 

Do.  do.     three        do        2500 

Stage  micrometer,  ruled  100  and  1,000 3  00 

Maltwood's  object  finder,  in  case 3  00 

Forceps,  straight  and  curved 25c.  to  2  00 

Stage  tweezers,  on  jointed  arm 3  50 

Glass  polyp  trough,  complete 4  00 

Live  boxes,  for  insects,  etc 3  50 

Animalcule  or  dipping  tubes 10 

Frog  and  fish  plate,  complete  in  glass  or  meta     $2  50  to  4  50 

Glass  fish  boxes 3  00 

Glass  stage  plates,  various 50c.  and  1  25 

Spring  compressorium,  $6  00 ;  do  for  high  power 4  00 

Best  lever      do.  §16  00;  inverting  do 10  00 

Edward's  prism,  for  oblique  illumination,  mounted  in  German  silver $40  00  and  50  00 

Read's  prism. . .  12  00 


PRICE-LISTS    OF    MICROSCOPE    FIRMS.  (357 


No.  19. — Price-List  of  Microscopes  and  Microscopic  Apparatus  of  T.  H.  Mc- 
ALLISTKR,  49  Nassau  Street,  New  York     (1872). 

Professional  microscope.  Somewhat  more  than  15  inches  high  ;  base  of  iron  lackered,  with 
uprights  to  receive  the  axis  upon  which  the  body  inclines  to  any  convenient  angle :  body 
of  brass,  finely  finished  with  extension  draw-tube.  Coarse  adjustment  by  a  delicate  watch- 
chain,  controlled  by  a  large  milled  head  on  each  side  of  the  tube :  far  more  efficient  and 
precise  than  the  majority  of  rack  movements ;  will  readily  adjust  for  all  but  very  highest 
powers:  fine  adjustment  by  micrometer  screw.  Stage  large  and  steady,  but  thin  enough 
to  allow  extreme  obliquity  of  illumination.  To  upper  surface  a  plate  glass  stage  is 
attached ;  can  be  freely  moved  in  vertical  and  horizontal  directions,  can  also  be  revolved  ; 
the  motion  is  so  delicace  and  simple  that  many  experienced  microscopists  prefer  it  to 
elaborate  screw  stage  ;  a  movement  as  minute  as  1-12,000  can  be  effected  by  it.  A  brass 
rest,  with  springs  to  hold  the  object,  is  clamped  to  it,  but  can  be  removed  in  a  moment, 
leaving  a  clean  glass  plato  for  examination  of  recent  anatomical  preparations,  chemicals 
or  other  substances  which  would  injure  the  usual  brass  stage.  Beneath  the  stage  is  a 
separable  collnr  carrying  the  diaphragm,  and  also  adapted  to  receive  the  polarizer,  para- 
bolic illumnator  and  other  accessories..  Concave  and  plane  mirrors  mounted  with  univer- 
sal motion,  and  slide  on  a  jointed  bar  for  direct  or  oblique  illumination.  The  fitting  for 
the  objectives  is  made  with  the  "London  Society'1  screw,  so  that  objectives  of  all  first- 
class  makers  can  be  used  with  the  instrument.  Stand  with  two  eye-pieces,  but  without 
other  accessories,  in  neat  upright  walnut  case,  with  lock  and  handle $75  00 

Student's  Microscope  ;  somewhat  more  than  12  in.  high  :  base  of  iron  lackered,  with  uprights 
to  receive  the  axis  upon  which  the  body  inclines ;  tube  of  brass,  with  extension  draw-tube ; 
coarse  adjustment  by  delicate  watch-chain,  controlled  by  large  milled  heads  on  each  side 
of  tube ;  fine  micrometer  adjustment  attached  to  stage  ;  stage  of  brass,  with  brass  springs 
to  hold  the  object,  diaphragm  plate  beneath  ;  stage  forceps  attached  to  stage,  which  are 
convenient  for  holding  an  insect,  flowers,  etc.,  while  being  examined  by  low  powers;  con- 
cave and  plane  mirrors  with  universal  motion  on  jointed  bar.  'With  following  accessories : 
one  eye-piece :  1  in.  achromatic  objective  ;  ^4  in.  do. :  magnifying  powers,  50,  75,  250  and 
400  diam. ;  in  neat  upright  walnut  case,  with  lock  and  handle $50  00 

Popular  microscope ;  somewhat  more  than  10  in.  high  ;  base  of  iron  lackered,  with  uprights  . 
to  receive  axis  on  which  the  body  inclines;  tube  of  brass,  with  extension  draw-tube, 
milled  head,  fine  adjusting  focus ;  stage  of  brass,  with  springs  to  hold  object,  and  with 
diaphragm  plate  beneath  ;  stage  forceps  attached  to  stage  ;  mirror  mounted  with  universal 
motion  on  jointed  bar.  With  following  accessories  :  one  eye-piece  ;  one  achromatic  objec- 
tive, separable ;  magnifying  powers,  50,  75,  150  and  200  diam. ;  in  neat  upright  walnut 
case,  with  handle $25  00 

Objectives,  etc..  of  first  makers  on  hand,  and  for  sale  at  manufacturer's  prices. 


Microscopic  Accessories. 

Bull's-eye  condensing  lens  on  stand,  large  size,  fine  finish — adapted  for  the  "Grand  American," 

or  the  "  Professional "  microscope $10  00 

Bull's-eye  condensing  lens  on  stand,  adapted  for  ''The  Student's"  or  the  "Popular"  micro- 
scope      5  00 

Bull's-eye  condensing  lens  on  stand,  adapted  for  "  The  Household  "  microscope 2  50 

Polarizing  apparatus,  adapted  for  ' '  The  Grand  American  "  microscope 35  00 

Polarizing  apparatus,  adapted  for  "  The  Professional "  microscope 25  00 

Polarizing  apparatus,  adapted  for  "  The  Student's  "  microscope 20  00 

Polarizing  apparatus,  adapted  for  "  The  Popular  "  microscope 15  00 

Selenite  plate 1  00 

Zentmayer's  achromatic  condenser 38  00 

Zentmayer's  achromatic  oblique  prism 14  00 

Zentmayer's  Amici  prism 10  00 

Camera  lucida 8  00 

Parabolic  illuminator,  adapted  for  "  The  Grand  American  "  microscope 14  00 

Parabolic  illuminator,  adapted  for  "  The  Professional  •'  microscope 10  00 

Erector,  or  reducing  eye-piece,  for  erecting  the  image,  redticing  the  power,  and  enlarging  the 
field  of  view — adapted  for   "The  Grand  American,"    "The  Professional"   and   "The 

Student's  "  microscope 7  00 

Concave  amplifier,  for  increasing  the  power 5  00 

Stage  forceps. 4  00 

Animalcule  cage 4  00 

Zoophyte  trough  of  glass 4  00 

Stage  micrometer,  1-100  and  1-1000 2  00 

Eye-piece  micrometer,  with  micrometer  screw 6  00 

Malt  wood  finder,  for  ascertaining  and  registering  the  position  of  any  particular  object  in  a 

slide 5  00 

German  student's  lamp  for  burning  coal  oil.  affording  the  best  light  for  microscopic  investiga- 
tions      7  00 

42 


658  PKICE-LISTS    OF   MICROSCOPE   FIEMS. 


Materials  for  Mounting  Objects. 

Plate  glass  slides,  3  by  1  inch,  ground  edges per  dozen  $    75 

Thin  glass  circular  covers,  1  inch  diameter do.  75 

Do.                 do.           %        do do.  50 

Do.                  do.            %        do.            do.  40 

Do.                  do.            %        do.            do.  40 

Canada  balsam per  bottle  50 

Gold  size ^ ^ do.  '    50 

Brunswick  black. do.  50 

Marine  glue 25 

Shadbolt's  turn  table 4  00 

Steel  forceps,  4  inch  long,  straight  points 1  00 

Do.                   do.          curved  points 1  00 

Scissors,  4%  inch  long,  straight  points 1  50 

Do.                do.            curved  points 150 

Prof.  Valentine's  double-bladed  knife,  for  making  fine  sections  of  soft  tissues,  etc 8  00 

Case  of  dissecting  instruments 10  25 

Needle-holder,  with  binding  screw , 75 

Needle  in  steel  handle 25 

Scalpel 75 

Dropping  and  dipping  tubes 10 

Cabinets  for  Holding  Objects. 

To  hold  6  dozen  objects,  mahogny  case $4  00 

Do.      2    do.        do.      case  covered  with  cloth,  lined  with  velvet 75 

Do.      2    do.        do.      plain  case 25 

Do.    10  objects,  do 15 

Do.       6      do.  do 10 

Do.      1      do.  do.      (for  mailing,  etc.)  per  doz 80 

No.  20.—  Price-  List  of  B.  PIKE'S  SON,  518  Broadway,  N.  T.  (1872). 

Student's  microscope ;  15  inches  high,  weighs  5  Ibs. ;  iron  base  and  arm :  rack  and  pinion  for 
coarse  adjustment,  fine  by  screw  with  lever  to  stage  :  stage  of  glass,  sliding  by  hand  :  plane 
and  concave  mirror ;  A  and  B  eye-pieces ;  1  in.  and  %  in.  objectives  ;  magnifies  from  50 
to  600  diam. ;  has  a  condensing  lens  on  a  stand ;  mahogany  case $75  00 

Physicim's  microscope;  same  height  and  weight  as  the  preceding  one;  iron  base ;  coarse 
adjustment  by  chain  movement,  fine  by  screw  with  lever  to  compound  body ;  stage  of 
glass,  sliding  by  hand,  double  mirror;  A  and  B  eye-pieces;  1  in.  and  %  in.  objectives; 
magnifying  power  from  50-960  diameters ;  condensing  lens  on  stand,  and  draw-tube,  with 
case $100  00 

No.  21. — Price-List  of  Microscopes  of  JAS.  W.  QUEEN  &  Co.,  924  Chestnut 
Street,  Philadelphia,  and  535  Broadway,  New  York  (1872). 

Student's  microscope ;  14  in.  high,  weighs  5  Ibs. ;  iron  base  and  arm ;  coarse  adjustment  by 
sliding  the  tube  with  the  hand,  fine  by  screw  with  lever  to  nose-piece ;  stage  of  glass,  slid- 
ing by  hand  with  fitting  for  accessories ;  has  a  plane  and  concave  mirror  with  hinge  move- 
ment; one  eye-piece  ;  one  objective  of  1-5  in.  (dividing);  magnifies  from  100-300  diam. : 
stage-micrometer  and  condensing  lens  on  stand  :  with  case $65  00 

The  same,  with  two  eye-pieces  :  1  in.  objective  of  18°  and  1-5  in.  of  80°  ang.  aperture  ;  magni- 
fying 50-500  diameters  ;  stage  micrometer,  condensing  lens  on  stand,  camera  lucida,  and 
compressormm.  In  a  case -  $100  00 


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